April - August 2007 :

	Hi,

	You liked to turn LargeSystemCache on your WinXP ?
	You were wrong ! :>
	Read http://support.microsoft.com/kb/895932 and turn it back off quickly !

" When you enable System cache mode on a computer that uses Unified Memory
Architecture (UMA)-based video hardware or an Accelerated Graphics Port (AGP),
you may experience a severe and random decrease in performance. For example,
this decrease in performance can include very slow system performance, stop
errors, an inability to start the computer, devices or applications that do not
load, and system instability. "

	So, as you see, despite that control is exposed by Windows UI,
	it is in no way intended to be used for your benefit.
	Keep it turned off, i.e. optimize memory usage for programs,
	not for system cache. It is documented by Microsoft that you could 
	become unhappy by disobeying :>

--- below is the old version of this page, for historical purposes ---

	Are you sure that you entry-level PC is good enough ?
	Are you sure that your HW vendor did the proper testing ?
	You can have a very unpleasant chance to stumble on data-corruption
	error that is not easily detectable by most of narrow-scoped HW tests.

	Here is a combined testcase for your consideration, which can help you
	to discover these errors before they do a significant harm :

	1. Take a SATA or ATA HDD of 80 or more GB.
		Take a clean HDD without valuable data since you are going to test
		potential data corruption.
	2. Take an entry-level motherboard, with i945GZ (or -GC) chipset.
		Good candidates are Gigabyte 8I945GZME or ASUS P5GZ.
		(August 2007: As well, this was observed on Gigabyte 945GCM-S2 mobo.
		And later in this month, the same happened on good old Asus P4P800-SE mobo,
		after its RAM was upgraded from 256 to 512 MB)
		Other chipsets could not give you the whole described fault.
	3. Add DDR or DDR2 module (I had single PC2-5300 DIMM on 512MB from Samsung)
		(Probably 512 MB is important, as your fault chances could be lower
			with 256 or 1024 or other total amount of RAM
		Single 512 or two 256, seem do not matter much)
	   Add CPU (I had Celeron 2.53GHz with socket 775)
	   Add necessary fans and heatsinks
	   Add CD/DVD drive
	   Add power supply
	   Add keyboard and mouse
	4. Almost ready now. Install Windows XP SP2 OEM on this system.
		Don't activate it after install, or else you can potentially 
		lose your online activation and have to activate by phone.
		I don't know if other XPs/Vistas/2ks will show you the effect.
		And please don't yet install motherboard-specific drivers 
		on this step !
	5. On first usable boot, open My Computer properties, 
		or Control Panel - System, go to Advanced tab, 
		and press Settings button in Performance section
	6. In the shown dialog, go to another Advanced tab, there switch 
		"Memory usage" to "System cache". 
		This control is exposed by Windows GUI,
		so we could turn it on without pain, right ? :>
	7. Now you are very close to the moment of truth. 
		Press OK in all dialogs and restart the system.
		Usually this restart should be normal.
		Now install motherboard-specific drivers, 
		restarting the system as they ask you to do.
	8. If you were able to install all drivers without corrupting your
		profile or registry, you may consider yourself almost lucky
		and your iron almost good. However go on 
		and put a combined load on your system :
	9. Put it on the network, include it into a domain if you have to,
		and copy some files from the network share onto your local
		disk. The important thing is the volume of copied data.
		Good number is about 4*your RAM volume,
		i.e. about 2 GB of copied data for 512 MB of RAM.
		While you are copying, do something locally-intensive,
		like install Office (2003 SBE worked for me),
		run its programs for the first time, type something in,
		close them, play sol.exe, etc.
		Of course don't activate Office, as testing is not yet complete.
		After this all is finished, restart your system again.

	Now, if you still don't have corrupted your registry/profile,
	you are completely lucky and your iron is as well as it should be.

	If you have corruption (strange messages from Windows, 
	or unbootable system at all), then probably you should avoid using 
	this LargeSystemCache mode. It's just not for your chosen iron.

	In my case, the problem was solved by replacing the mobo in my system 
	with ASUS P5V-VM Ultra (chipset VIA P4M890).

	Don't know, may be VIA chipset developers did more thorough testing that Intel ones ?

	Surely these faults do not depend on network adapter driver,
	as 8I945GZME, P5GZ and P4P800 used Marvell Yukon,
	and 945GCM used Realtek 8169. All crippled chipsets were Intel,
	945 series as well as 865. Of course there are lot of Intel chipsets
	that are impeccable. Every time, this was observed with 512 MB of RAM.
	Once, with P4P800, it was not observable with 256 MB RAM,
	but emerged after upgrading it to 512. Once I long enjoyed i865-based system
	(may be even the same P4P800) with 1GB RAM and LargeSystemCache turned on,
	without any problems.

	May be we should wait for BIOS or drivers updates from the vendors.
	If you are the buyer, you should decide. 
	You have a testcase, know it and use it.
	Wish you luck with your new iron.

	mwg@mwg.dp.ua - feel free to drop me a note about this page.