What if my System refuses to boot ?
A1. If your system simply hangs after the BIOS with no error message, one of your hard disk drives may have become 'corrupted' or may have totally failed. Don't assume it's your 'boot' drive - modern motherboard SATA controllers are quite capable of 'hanging' the system by attempting to 'boot' from a broken or invalid drive EVEN IF your normal system C: drive is perfectly OK !
Before you panic, remember that most people set their BIOS 'boot order' to CD/DVD first - so a 'boot lock-up' can be caused by having a CD / DVD disc in your CD/DVD drive !
Those who have set 'USB device' as the second boot choice may discover their system 'locks up' when they power-on with a USB stick (or USB 'external drive') or even a Memory card (SDHC etc) inserted ....
So, the first step in diagnosing a boot fail is to check for CD/DVD discs - and unplug your USB devices. Only if it still fails should you open the case and start unplugging hard drives.
NB. The data on a 'failed' D: drive that is preventing C: from booting may still be 'accessible' if you connect it AFTER boot-up to a PCI controller or external USB enclosure that supports 'hot plugging'.
Even though most motherboards typically don't support 'hot plugging', you can often 'get away with it' (i.e. after boot, plug in the data cable of the 'suspect' drive).
A2. If you get 'Operating System Not Found', 'Invalid System Disk' or the ever helpful 'Missing NTOSKERNAL' error message, use the Windows Recovery Console to 'repair boot sectors'. This is an option that can be selected from any bootable MS System Installation CD/DVD (although it is often called something else - for example, on the Windows 7 install DVD it's 'Repair a non-booting system')
When you power-on and the 'Choose an Operating System' list appears, one option you should always have access to is "Windows Recovery Console".
If not, install it now from your Windows XP System CD. Fortunately, Microsoft does a good job of explaining How to install the Recovery Console. Yep, this is one more thing you really need to do BEFORE your system crashes (rather than after :-) )
Problems with a RAID Mirror ?
A1. Sometimes a hard disk will 'degrade' gradually, often without you noticing, as the Operating System automatically performs 'retries' and 'marks' more and more of the disk surface as 'bad'. Multiple retries introduce access delays and may even be heard as a 'ticking' sound, however if your Server is locked away (as it should be) you can miss this 'early warning'
You should examine your Event Logs every month or two. If this shows multiple disk read/write failures you should take action before the drive fails completely, even if it's only the ordering of replacement drives :-)
A2. As you will know, Microsoft RAID Mirror requires that the disks be set to 'Dynamic' (most low-end RAID cards just use the MS approach) - and occasionally Windows will insist that a 'dynamic' hard drive is 'invalid' - and, of course, there's a 50/50 chance it will then refuse to boot.
A RAID Mirror still consists of 2 physical drives, one of which will be the 'boot' (C:) drive and the other the 'clone'. The 'clone' is, of course, 'only' accessible once your Windows System is up and running. The 'boot' drive is the FIRST seen by the BIOS ("SATA 0"). So if your system C: RAID Mirror fails to boot, try swapping the cables !
Of course Windows being Windows, if one of a RAID Mirror data set becomes inaccessible, Windows will refuse to access the other !
This is yet another MS 'joke' = the user is fooled into setting up a RAID Mirror for their precious data in the hope of improving system reliability, where-as what they are actually doing is making it more than twice as likely to fail !
The only 'solution' is to place both drives into another system (or boot from a 3rd 'drive' - modern motherboards can boot direct from a USB stick)
Once you have access to the drive(s) in a booting system, in Disk Manager, see if you can get the RAID Mirror set back using the 'Import foreign disk' option. If 'Reactivate' fails (as it often does with a "This operation is not allowed on the invalid disk pack" error) Windows will only offer you the choice of loosing everything with "Convert to Basic" (and then creating new partition(s) and reformatting).
Of course there is a very good chance that at least one of the pair has a perfectly good directory structure and, if only Windows would allow access, you would be able to copy everything off.
To get access, you do need to convert it back to 'Basic' HOWEVER Windows itself won't allow this without wiping everything ! So you have to manually edit the disk partition table (see below)
Converting from Dynamic back to Basic
Microsoft states this "can't be done", however that's the usual half-truth. The Dynamic directory structure is compatible with Basic ONLY if you used 'dynamic' to set-up your RAID Mirror (and not for 'spanning' or 'extending' partitions etc). If that's the case, all you have to do is change one 'magic' byte in the drive partition table :-)
Start by downloading HxD disk hex editor (freeware).
'Open' the 'offending' disk. In sector 0, location 1C2, the value should read "42" = this means 'Dynamic' disk.
Change the value to "07" (Basic Disk), save the changes and then reboot so that Windows can 'find' the disk.
(a second reboot may be needed for Windows to assign a drive letter and show it in 'My Computer')
HxD only works on disks 'seen' by the BIOS as 'directly connected'. So drives on a PCI card with built in BIOS that supports 'boot' functions should be 'seen', however drives on cheaper 'RAID' cards or an external enclosure linked via USB will NOT be seen (even if the motherboard supports 'boot from USB')
Fortunately almost all cheap 'RAID' cards (and external USB linked enclosures) just 'present' their drives to the standard Windows disk drive RAID utilities. This means all you have to do is move the 'RAID' drive to a motherboard SATA socket and, so long as the drive is physically 'seen' by the BIOS, HxD should be able to access the drive.
NAS drives
Unfortunately, the drives in a 'stand-alone' NAS (that's accessed via Ethernet) are typically NOT 'standard Windows' (NTFS) formatted. Instead the NAS will almost certainly be running some flavour of LINUX and the hard drives formatted with an Open Source partitioning and directory structure.
To access these under Windows you will need the appropriate Open Source drivers/utilities (the first place to look is on the NAS manufacturers own web-site, since it will be 'in their interests' to provide customers with data recovery tools).
How do I recover from a corrupted System ?
A RAID MIRROR simply duplicates data, so if Windows (or you) manage to corrupt somethig vital (typically, something in the Registry - usually the drivers being used for your hardware), you just end up with two copies of the corrupted data. So, FIRST try 'F8' and 'Last Known Good'. Next try 'Reset to previous System Restore Point', then restore from your latest System Backup and finally a Repair Install (using the Operating System CD).
Finally, before giving up (and doing a total reformat and re-install), you should use HDD Guru (or one of the many other free or Open Source) hard drive recovery tools to get what data you can off the drive first
Recovering from a total hard disk failure
With a RAID MIRROR, when the first disk fails, you should use the remaining 'good' disk to copy your system to a PAIR of brand new disks.
Why replace both RAID disks ?
If one disk of a pair that is 5 years (or older) is 'toast', how long will it be before the second one goes ?
More to the point, disk technology is advancing every year = so after 5 years the chances of you finding an 'identical' replacement for the broken one will be effectively zero anyway.
However, perhaps more important than anything else, the last thing you want to do is risk the data on your remaining good disk whilst 'repairing' your MIRROR
This, by the way, is one reason to stick to Windows RAID, rather than same fancy NAS box. When a NAS drive fails, all you can do is replace the drive and prey that the 'never used' built in 'Repair' function actually 'works' ...
To create a new C: MIRROR :-
On your Windows Server/NAS (or an existing PC), see Setting up RAID on Server/NAS
In short, boot the Clonezilla Live CD, take an 'image' of your working C: & save it onto one of the new drives, then UNPLUG your old C: and build the RAID). In this way, if anything goes wrong, you still have all your data (on the surviving original C: drive you unplugged).
On a brand new PC, see Setting up RAID on a new PC
More complex because you should install Recovery Console and remove the 'auto-run' traps ('free' junk software installers) etc. first)
What to do if my Motherboard fails ?
Of course, ideally you replace the broken motherboard with an identical replacement. However most of us will want to take the opportunity to 'upgrade' our system at the same time - and, if you want to avoid paying Microsoft $$$$ for a new licence you need to proceed carefully
If you have a 'full retail licence' version of Windows, all you need to do is 're-activate' the licence on the new motherboard (if necessary, phone Microsoft).
If you have an 'OEM licence' version, Windows is 'auto-activated' simply by the presence of the motherboard itself. The OEM XP licence is actually quite 'flexible' in that it will typically accept virtually any 'newer' motherboard from the same manufacturer - but that's not the case when you switch manufacturers - and it's not unusual to discover other manufacturers motherboards are a lot more 'functional' and/or quite a lot cheaper (and easier to find) on eBay than the one you have
Switching to another OEM motherboard
Plainly any replacement motherboard has to fit your existing case. Fortunately manufacturers have stopped using propitiatory case / motherboard mounting arrangements, however you do need to watch out for things like the number of PCI slots supported, although again manufacturers now tend to stick to 'standard' layouts. For example, the Dell Dimension range uses micro-BTX motherboard layout - the Dimension 3100 has a motherboard with 3 'slots' but a case that has room for 4 (the case is actually common with the Dimension 51xx that has a 4 slot motherboard)
Your Windows XP System COA 'licence' is only 'valid'** on the original manufacturer's motherboard - so if you have a Dell, you can 'migrate' to another Dell - but "not" to HP etc. Whilst your existing hard drive will usually 'boot up' on a different manufacturers motherboard it will then halt' with a 'You must activate Windows now' before allowing you to log-in.
If you attempt to re-install Windows using one 'OEM' manufacturers Windows System Restore CD (eg Dell), it will refuse to install on a hard drive connected to a motherboard from a different manufacturer (eg HP). The same applies to a 'full retail Licence' = this will not install Windows XP on an OEM motherboard (nor can it be used to 'activate' Windows, not even if you ring up Microsoft and beg)
** The COA 'Licence Key' sticker on the back of the case is a 'dummy' (and can't be used to 'activate' Windows at all) .. the 'real' OEM Licence Key is on the OEM System disc, and this OEM Licence key is 'locked' to the specific manufacturer's BIOS. So, for example, a Dell System CD can't be used with a HP motherboard because it will only complete the install if it finds a Dell BIOS 'signature'.
Of course, when I purchased my OEM computer, I paid Microsoft for an OEM Licence. So I see no moral reason why I should pay for another Licence just because one OEM motherboard fails and I want to replace it with another one.
Fortunately it's a relatively simple job to 'switch' to a different OEMs' motherboard, although switching to a 'non-OEM' motherboard is virtually impossible (which is as it should be, since the OEM motherboard vendor will have paid MS for an OEM Licence, whilst the non-OEM motherboard manufacturer will never have paid MS for any sort of Licence)
Note that the Windows XP Licence remains the 'property' of the original purchaser (you). When you buy a second-hand OEM XP motherboard, you are not buying another OEM Licence, so, to stay legal, can only use it to replace an existing motherboard. If you want to buy another OEM XP Licence, you will have to buy the OEM Windows System disk. However for Windows 7, it seems that the OEM Licence is 'sold with the motherboard'. So Microsoft allows you to download Windows 7 from their on-line distributors and that this will install and 'auto-activate' on any Windows 7 capable OEM motherboard without 'asking' for any Licence key (see 'Can I upgrade to Windows 7 ?' below).
How to 'boot' on a different OEM motherboard
To get your system drive up and running again, you need to change the 'OEM files' (and OEM Licence key) on your existing system hard drive to 'match' the new motherboard. You can do this by plugging the drive into another PC (as a data drive) or by booting to the Recovery Console or by using a 'Live CD'
The 4 OEM files have to be replaced in :-
C:\windows\system32\ oembios.bin, oembios.dat and oembios.sig
C:\windows\system32\CatRoot\{F750E6C3-38EE-11D1-85E5-00C04FC295EE}\ OEMBIOS.CAT
[if they exist in C:\Windows\System32\dllcache\, all 4 i.e. oembios.bin, oembios.dat, oembios.sig and OEMBIOS.CAT]
For most manufacturers OEM motherboards, these files can be found on the Internet (see below re: use OEMBIOS tool (v1.1) to discover your exact OEM BIOS and then use Google etc. to find the files = for example for Gateway BIOS sig. A04597C6 Google for 'OEM A04597C6')
The 4 files in the OEM file set will be about 12.5Mb in total and will typically be 'zipped up'.
If you are offered an .exe file or a package that is significantly less, this will be a 'stub' or 'download tool' designed to 'hide' what's actually being downloaded. Often it will be an 'adware' tool - designed to take over your browser and redirect your 'searchs' to their advertising spam servers == however sometimes it's somrthing much more dangerous.
Todays criminal scam sites can 'auto-generate' link 'names' for whatever you are looking and then 'present' you with their Root Kit / Trojan / Virus downloader with a 'name' that appears 'genuine'.
NEVER fool for this trick = whilst you may only be spammed (or infected with 'ad-ware' i.e. sent a 'home page hi-jacker' or have your web browser 'search' redirected to some advertising site), anything ".exe" you download could contain a key-logger, root kit or virus.
Of cousre if you left Windows View Options on the default mode ('Hide file extensions'), you will never be able to tell the difference between a 'real_file.zip' and 'root_kit.zip.exe' anyway.
You should** also replace your OEM 'manufacturer specific' Licence key with the Microsoft XP non-specific OEM key (use key MVF4D-W774K-MC4VM-QY6XY-R38TB for all versions of XP 32bit). Needless to say, it's not just a matter of replacing a string in the Registry - there are two 'licence files' that have to be generated, however Microsoft provides a tool to do this, although you will be able to boot up and log-in OK without bothering with this step
**Later, when downloading MS Updates, you may be asked to run the 'Genuine licence validity checker'. If this spots the fact that you are using one manufacturers OEM licence key on a different manufacturers motherboard, 'validation' will fail - and you will have to install the non-OEM specific key anyway
Once you have the Licence issues sorted out, Windows XP will allow you to 'log-in' and you can replace the old motherboard drivers with ones for the new motherboard - in the unlikely event that the old drivers 'lock up' the new motherboard, you will have to boot into Safe Mode to replace them
Single to multi-core CPU
If your system is really 'ancient' it may be running on a very old motherboard with no support for 'Sleep' or 'Hibernate'. If this is the case, switching to a 'modern' multi-core motherboard with these features will require a full re-install of XP. In that case, see below re: creating a new OEM System Install CD
If your old system was 'single' threaded (i.e. single core CPU with no hyper-threading) and your new motherboard has a hyper-threaded or multi-core CPU, you need to make a change to the boot.ini file in order to select the multi-threaded kernel at boot time
First check in c:\windows\system32 that you have the multi-threaded 'hal' (halmacpi) and 'kernel ' (ntkrnlmp) - if not, go find them (they may already be in \i386 - if not, you can 'extract' them from 'sp3.cab' using 7zip) and put them in c:\windows\system32
Now modify boot.ini to give yourself the multi-CPU option at boot up ....
Find the line :-
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /fastdetect /NoExecute=OptIn
COPY it and modify the copy to read as below :-
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP MultiCore" /fastdetect /NoExecute=OptIn /kernel=ntkrnlmp.exe /hal=halmacpi.dll
You now have a choice of two at boot up. Once you are happy it's working OK, you can delete the first (single threaded) option
Your Windows XP Home licence allows you to run 'all' the cores on a single CPU 'socket'. XP Pro is licenced for 'all' the cores on two CPU 'sockets'. As with all Microsoft 32bit Operating Systems, you are limited to a total of 32 'logical' CPU's (i.e. 32 actual cores or 16 cores running hyper-threaded).
Note that MS has removed many of the XP information pages from it's web site (presumably so people 'forget' what XP was capable of) and even those that remain are somewhat 'misleading'. For example, in Microsoft's comparison of XP 64 and 32bit 'Number of processors' actually means 'Number of CPU sockets' (as revealed in the 'Notes' about local processors). Worse, the term 'Physical RAM' is used when the limitation is actually 'Physical address limit' (of which 750 Mb is typically allocated to I/O space and thus unavailable for physical RAM usage)
Modify your existing OEM System CD for a new OEM motherboard
All you need to do is swap over the OEM files and the Licence key (as per above). The only slightly complex bit is that the OEM files have to be 'correctly' packed into MS .cab structure (the Licence key goes into the Winnt.sif file). For a full explanation, see here (you need to follow the first link to get the bootable DOS floppy "OEMBIOS tool (v1.1)" which will tell you exactly which OEM file set you need (for example, Gateway motherboard = C86378C7) - then you will need to go find the oem files (for example, if your new motherboard is a Gateway, Google for 'C86378C7'), and download them (most likely via anonymous torrent, now that Microsoft has started to actively suppress the file sets)
Why has MS suppressed the OEM files ? - after all, haven't they already been paid a Licence fee for every OEM motherboard that has ever been sold ? Well, actually, no, since there was a time when PC manufacturers would sell you a Linux PC (i.e. without a MS Licence) but left the motherboard BIOS set to 'Microsoft OEM' status
Some systems would also have only been sold with 'XP Home' (although there never was anything that stopped you installing XP Pro on those motherboards, other than lacking access to an XP Pro OEM install disk).
On the other hand, the rather more cynical believe that MS is trying to make it as hard as possible for XP users to keep their systems running and so 'encourage' them to purchase a whole new system (and thus pay for a Windows 7 (or 8) Licence). If you decide to go this route, see below
Start with an ISO image of your existing OEM System CD (to preserve the 'boot' capability) then use PowerISO, UltraISO or MagicISO or similar to unpack the ISO, change the OEM files and winnt.sif and repack the ISO. You can then burn your new system CD
The alternative is, of course, to simply purchase a replacement OEM System CD (for the new motherboard) from eBay. DO NOT be tempted to download some 'hacked' CD = it WILL come with key loggers and root kits 'pre-installed'
Other issues
Many OEM manufacturers attempt to convince you that their components are in some way 'special' and thus justify charging an arm & a leg for 'special replacements'. Fortunately, in the vast majority of cases they actually use standard components but just 'wire them up' differently
There was a time when Dell, for example, would use non-standard PSU connector wiring - this, presumably, to prevent customers replacing the inadequate Dell PSU with something a bit more powerful. Fortunately their PSU wiring is now standard
Dell CPU fan wiring
Dell still wire up their CPU fans in a non-standard way. Fortunately their 4 wire fan / 5 pin plug can be simply re-wired (and, after re-wiring, their 5pin plug can be pushed into a standard 4 pin motherboard header).
| Dell 5pin fan plug | ||||
| Yellow (or White) | Red | Black | Blue | n.c. |
| sens | +12v | Gnd | pwm | n.c. |
| Standard 4pin fan (pin header strip) | ||||
| 1 | 2 | 3 | 4 | |
| Gnd | +12v | sens | pwm | |
Needless to say, if you are switching from a Dell motherboard to a different OEM motherboard, that manufacturers motherboard fan 'header strip' may also differ from the 'Standard' ..
Dell 'Flex-bay' multi-media reader / TEAC CA-200
There are (at least) two 'types' of Flex-bay multi-media option 'in use' by Dell, both occupying the 'floppy disc' position. One consists of SD card etc. slots only - the other has both USB and card slots. Both use a 10pin ribbon cable & plug. One requires a single USB connection at the motherboard, the other 2.
The Dell Dimension series 'Flex-bay' (multi-media only i.e. no integrated USB sockets) uses a single USB header. The motherboard / cable pin-out is as follows :-
| pin 1 | +5v | 2 | |
| (3) | (missing) | 4 | |
| 5 | 6 | ||
| 7 | D- | 8 | |
| 9 | D+ | Gnd | pin 10 |
The Dell "HD273" used in the Optiplex (GX620 GX520 755 760), Inspiron (530s, 530) and Vostro 200 400 XN068 NT424 WY345 range is the "TEAC CA-200". Needless to say, it's a non-standard pin-out at the non-standard 'miniature' (2mm pin spacing rather than the standard 2.5mm) 10-pin ribbon socket. Apparently it is wired to use 2 USB connections (despite the fact that it has no 'USB out' sockets, only multi-media card sockets), HOWEVER some reports suggest you can 'get away' with wiring in the first set (and ignoring the second set)
If you must use this POS, I suggest you pop it open, remove the non-standard 10pin socket and it's pointless 'daughter board' and wire direct to the main board. The colours below are for the wires 'inside the unit'
TEAC CA-200 non-standard 10pin header (NOTE = this didn't work for me = you may have better luck)
| pin 1 | Gnd (shield / clear) | 1.D- (green) | 2 |
| 3 | 1.D+ (white) | 4 | |
| 5 | Gnd (black) | 2.D+ (yellow) | 6 |
| 7 | 8 | ||
| 9 | +5v (red) | 2.D- (blue) | pin 10 |
Multi-media readers are so cheap that I ended up replacing my Dell unit with an 'off the shelf' one which not only came with a standard motherboard pin connector cable but also had a pair of USB sockets
What about the 'front panel' connections' ?
Of course the propitiatory front panel ribbon connection designed for one OEM's motherboard isn't going to fit another's, so you have the task of working out what pins connect to what LED's etc. The only really 'vital' one is the 'power' button - and maybe the front USB sockets (if your new motherboard has 'spare' USB pin strips 'on-board' that would otherwise be unused).
Having traced the 'power' switch wires I quickly gave up with the rest of my front panel wiring and just ran 2 wires from the switch to the new motherboard 'PWR-ON' header pins. If you need more information, I suggest you try here
Can I use a non-OEM motherboard ?
No. You need a 'full retail' licence to run Windows on a non-OEM system manufacturers motherboard. This makes it virtually** impossible to replace your broken OEM motherboard with a non-OEM one without also paying for a full retail licence. My recommendation is "don't even try" - there are plenty of second-hand OEM XP motherboards on eBay, most of which are half the price of the equivalent non-OEM version
** The Windows XP licence system not only looks for a 'OEM Manufacturer ID string' in the BIOS but also reads the actual BIOS contents and 'matches' this against the 'OEM files' mentioned above. So, in effect, you would have to over-write the non-OEM BIOS with an OEM one.
Can I upgrade XP to Windows 7 instead ?
Yes, however unless you have a Windows 7 licenced OEM motherboard** you will need to buy a Windows 7 licence (of course). To qualify for the 'upgrade' price (rather than the 'full retail' price), Microsoft says you must 'have XP already installed' on your system. No mention is made of needing the XP System CD, however we can assume that the Windows 7 installer performs some sort of 'check' to see if your existing XP installation is 'valid' ... and if your hard disk is 'OEM licence locked' to your old broken motherboard, rather than the replacement, it's entirely possible that the installer 'upgrade check' will fail
** What if you buy a Windows 7 OEM motherboard as a replacement ? Well the OEM system manufacturer will have paid Microsoft for a licence to run Windows 7 on that motherboard, so no future user should ever need pay again = and so long as you use that manufacturers OEM licence key, you have Microsoft's blessing.
You can download Windows 7 Pro 32bit ISO from the MS on-line 'distribution' web site ('Digital River'), burn your own DVD and use it to install on your OEM Windows 7 motherboard without needing to pay MS anything. For this reason, second-hand OEM motherboards capable of running Windows 7 (i.e. those with 'SLIC 2.1' in the BIOS) are quite expensive :-)
Can I run XP on a Windows 7 OEM motherboard ?
Generally, yes. The only exception is likely to be a 'brand new' OEM company that has only just stated selling computers so they would never have paid MS for an OEM XP Licence (and would thus be shipping motherboards without the XP BIOS 'signature')
Even with older OEM's (such as Dell etc), before buying a 'current release' Windows 7 capable OEM motherboard, you should check that the XP OEM BIOS files (needed to run XP) exist for that specific motherboard. New motherboards that have never been sold with Windows XP may never have had the OEM check files 'generated' by the manufacturer
If you discover this after buying the board, you can install Windows 7 and run XP in 'emulation mode'
32 or 64 bit ?
If your motherboard is PAE capable (i.e. supports 8Gb RAM or above), and you install 4Gb or more of physical RAM, you should opt for 64bit Windows 7. Otherwise Windows will be limited to 3.25Gb of RAM (or less), since, no matter what 'miss-leading statements' MS may make, none of their 'Client' 32bit Operating Systems are able to access the whole physical 4Gb of RAM without being 'hacked' to bypass the Licence limit.
Every '4Gb' entry** in the MSDN table should more truthfully read "4Gb RAM less the address space allocated to i/o". Note that any 'unused' (aka 'missing' or 'OS invisible') RAM on a PAE capable motherboard can (only) be used by a (non-Microsoft) RAM Disk - which then allows it to be 'assigned' as Page File space, in effect returning the 'missing' RAM to the OS by the 'back door' :-)
** Actually, the same applies to all the 'memory limits' that Microsoft list.
For example, when MS says that 64bit Windows 7 'Home Basic' has a 'Physical memory limit' of 8Gb what it REALLY means is that Home Basic is "Licence limited to a maximum address space of 8Gb" (or, perhaps, even more accurately, "Licence limited to addressing 8Gb of physical RAM less the address space allocated to i/o").
Since modern motherboards allocate up to 1Gb for i/o, this means the 64bit Home Basic user typically only 'sees' a maximum of about 7.1Gb of physical RAM no matter what is fitted to the motherboard. Of course there is nothing to stop you using the 'invisible' RAM with a (non-Microsoft) RAM Disk driver and allocating it as Page File (Virtual Memory) space
On the other hand, if you choose to take MS web page wording at 'face value', it would seem that Microsoft can have no objection to you 'hacking' the 32bit Kernel in order to get access to a full 4Gb of 'Physical RAM' (just try it and see :-) )