G'day, whenever I play any games my system reboots after about 5-10 minutes of playing.
I can reproduce this most consistantyl by using the Quake 3 demo and having a skirmish with 10 or so bots, the system will reboot within 5 minutes garunteed.
I've had this problem for about 6 months now and I'm really getting sick of trying to figure out the problem.

My system specs are:
ASUS A7N8X-X Rev 2.00, BIOS Rev 1007
Barton 3000+
1 gig Kingmax DDR 400 RAM
GeForce FX 5600
WinXP

I have tried pretty much every combination of BIOS settings and this makes no difference.
I thought it might be a heat problem but I can run every Sandra benchmark aswell as 3D Mark 03 with the CPU getting up to 55 celcius, it has never rebooted in any benchmark.
When the system reboots during a game i have checked the CPU temp as soon as it's rebooted (15-20 seconds) and it's only 42 celcius max, so I don't think it's a heat problem.
I have updated the BIOS to Rev 1009 but this made the system too unstable to run the ram at 6-3-3-2 120%
so now I have downgraded to Rev 1007 and have left the ram at 8-4-4-2.5 100%
For months I couldn't use the onboard 6 channel sound support on my inspire 6600 speakers until ASUS gave me some drivers that made this work, however this made the system even more unstable again and the sound would not work properly in games, only for DVD's, so i'm stuck with using older drivers that don't support the hardware properly however the sound works perfectly for gaming.
I have updated every other driver I can think of but this doesn't stop the system rebooting.
Any help would be really appreciated.

P.S. I read somewhere that using 1 gig of ram (2 * 512 sticks) caused the board to heat up too fast however my board temp is never over 26 celcius so I don't think this is the problem.

Problem is your MOBO (ASUS A7N8X-X) or graphics card overheating.. maybe?
It's your mobo 99% sure of it. ASUS mobos are worst (the ones with X letters)

I had to set my memory to 83% of FSB. Everything went fine as of then.

My Athlon XP 3200 runs at round about 45 degree, I have the same motherboard as you and when I had an Athlon XP 2400 in it my computer used to reboot when playing games, the 2400 also ran at 55 degree when gaming, I went out and got a good coolermaster Heatsink and Fan my CPU temp dropped down to between 38 and 45 degree and never had any problems, Athlon will say 55 is OK there was even a guy on here who said he worked for Athlon and said that their CPU's run at 60 or 70 and that it is not a problem, but its not true, go out and get a good Heatsink and Fan to drop your temps and hopefully it will be OK, no matter what some will say 55 is to hot. do you get blue screens of death.

Yup, could well be heat.

Before you start with the Artic Silver though, yank out one of your memory modules and run it with a single Dimm-those boards have trouble running Dual Channel mode, and this is an easy way to test it.

If I had a pound for every time I've given this advice to people with an Nforce2 mobo-why, I'd be nearly as rich as Sander.

heres the deal, MS on Windows Update has Service Pack 1a still, it contains alot of fixes for general game problems and then there were updates after SP1a but before SP2 came out, well ms took those upates that came out after SP1a and put them in SP2, to manage resources of windows go to http://www.blackviper.com

Well that problem doesnt happen only with that motherboard..i've other (DFI NB71-BC) and the same thing happens to me, i still cant figure it out how to solve this problem, but this started to happening since i've changed my video card to asus fx5200 v9520 magic. somehow i solved the problem, but then i had some problems with win xp and ive done format. now i cant remember how to solve it again, strange huh?

Am I the only person who realizes how crappy the ASUS AN78X is!? 90% of our motherboard problems on this forum invole this board.

I have an ASUS and Im going to buy a Gigabyte board another thing I noticed with my mobo is that it doesn't like cheapish mice, I have a mouse that works perfect on 1 comp but on my ASUS it has a mind of its own.

this is fixed by running dxdiag.....click on sound....lower hardware acceleration 1 notch....roboot

I agree with this Ram is running to high. When I overclocked my system I had to turn down the Ram. Even though I had the Ram running at 200Mhz FSB the Buss was sending info too fast. Or should I say CPU. Turn down memory until you get stable. Let me know if this works.

Ive put 5 systems together utilising the A7N8X-X mobo. All are similar systems, utilising either AMD Athlon 3000 or 2800s, 512meg Kingston RAM and running XP Pro.

The first system, (my own) has a NVIDIA ti4200 video card with 128meg and have had no real issues (till recently)
The second system was for a work collegue. I put a Radeon 9600 Pro with 256meg in it, had no issues installing/running XP itself, but when playing games such as Dawn of War or DOOM3 for 10 to 30 mintues, the system would crash back to the desk top and and I would be presented with a "send VPU error report" prompt. Without going into detail, I tried evey fix I could find on the web, from changing AGP apeture size to flashing the mobo bios and everything inbetween. (Prior to setting up this sytem I had put two more together (for wife and daughter) using the same systems, except I installed Radeon 9550s. These ran fine)

At this stage I was coming to the conclusion that the motherboard, RAM or power supply may be faulty. I then uninstalled the 9550 from my daughters pc, placed the 9600 in it and it produced the exact same problem when running the games. (Now I was wondering if the 9600 was a faulty one). Just as an after thought, I uninstalled the 9600 drivers/software from original pc, put my daughters 9550 in it and was presented once more with the same problem the 9600 produced. Now I was coming to the conclusion that there must be a compatibility issue with the ASUS mobo and certain Radeon drivers.

To check this theory, I placed the 9600 in an older EPOX motherboard with a via chipset, clean install (for the 100th time) of XP, latest drivers, installed DOW and played it for six hours with a single glitch or hiccup!

The ASUS mobo I had swapped with the EPOX, I placed in my sons pc. He also had a 9550 and I assumed I wouldnt have any problems with it after a clean install of XP etc, seeing as how my wifes and daughters were running fine. This was not to be. XP installed fine, Dawn of war and other games would start ok, but the system would lock up after a small amount of time or, when exiting the game video corruption would occur and refreshing the screen would do little to help. I put this down to the bios update. Suffice it to say I had had enough of the ASUS A7N8X-X. I immediately went out and bought a ABIT mobo, (interestingly enough, with the same NFORCE chipset as the ASUS mobo), whipped it in, clean install of XP, latest drivers and NOT A SINGLE PROBLEM!!!! Infact, I am insanley jealous of my sons PC now as its got an AMD 2800, mine has a 3000 and yet his runs far better. The fact that he suffers nil problems playing 3d games is outshined by the fact that it runs them smoother and faster than three other systems, all with the same ASUS mobo, two with identical video cards as his.

As for why my wifes and daughters pc's run 9550's ok, eh..., but I wont be updating thier bios. I will be getting myself an abit mobo shorlty and I will be avoiding ASUS mobos forever.

ps: have discovered another system with A7N8X-X mobo, AMD 3000, 512 Kingston RAM using a Radeon 9600 running into problems playing 3d games. I see a trend developing here!
I

I have:
Asus A7N8X-X
AMD 3000+ Barton 400FSB
Maxtor uata/133 120gb
Saphire ATI Radeon 9800pro 128mb

First the problem I was having was with windows 2k, random reboots during any games. Anything from Q3 to simple Sponge bob games. I got so tired of it I tired going to a windows xp pro OS, but alas this was in vain. For when I tried to install it I couldnt even get it to go. After sometime and many hours of looking at forums and windows error code pages I deactivated the CPU L2 Cache on the board and BAM no more problems unfortunately this owns my comp speed which is unexceptible. I've tried everything I can think of and I'm about to whip out the voodoo goats blood and such. HELP ME, is there anything I can do to fix this stupid Cache Problem, or should I throw this stupid board out the window and get me a new one.