this is my first post to techspot,so HI! everyone.
my pc has been hanging randomly off late.the problem is a bit complex,ill write it down below,plz takt he patience to read through it.

i have a athlon64(single core) 3500+,asus a8n-e(nforce4) motherboard,1GB(2x512) DDR ram,asus 6600 grahics card,2 seagate 160gb sata hdds,1 LG pata dvd writer(GSA-H10A),Corsair VX450W power supply, running win xp pro with SP2 and all recent updates as of september 2007.
the motherboard has the latest bios.

the problem is that the system hangs randomly.someimtes it just freezes,and if there is any sound being played at that time,it keeps looping,
other times the cpu fan loses power,the usb peripherals lose power,but the hdd and mb onboard lan have power.and the monitor keeps cycling between low power(standby) and normal,without any picture.the problem occures randomly and i have been unable to recreate it at will.sometimes i hvae a uptime of 4-5 days before this happens,other times it happens 2-3 times in a single day.

suspecting the RAM i ran memtest for around 12 hours,not a single error was detected.then i ran ATITOOl in order to stress the graphics card,but after running this for around 8hours,i didnt find a single glitch.then i tried changing the power supply,but even with a diff power supply the pc still hanged.i tried reinstalling windows 4 times,always it has the problem.so ive determined that its not a software problem.i have the latest drivers from asus's website for the mb,and nvidia's site for the graphics card.having done this much,i felt that either the MB or the CPU were the culprits,i ran prime95 on the cpu for around 4hours,but no errors again.the system is not overheating.the cpu reports a temperature of 35C,mb is at 25C,graphics card is at 60C.the box is properly ventilated.

at this point i feel that this leaves out the mb or the cpu as the culprits.

i want ot know if i have missed anything,and if anyone here has had a similar problem.also,how do i isolate the problem any further ?.,

and is there anything i have missed ?

if anyone needs any further information,please make a reply to this thread and ill post whatever information you require.

1. Is your BIOS up to date?
2. Are all your drivers up to date? If you recently updated a driver and it starting acting flaky, the roll back to the last stable version.

Just a hunch, but try running it with just a single stick of ram for a while.

reply

thank you both for the replies.
the bios is up to date.the latest one version 1013 available on asus site.
drivers are also up to date.the problem did not start when i installed a flaky driver.its always been like this.

ill try running with a single stick of ram.
any other suggestions ?

You have an asus board as do I. Check your bios settings thoroughly and see if you are able to swap between dual channel and normal mode for your ram.
Asus mobo's can be very finnikey when it comes to ram, some brands work best set one way and other brands the other way. Some brands only seem to work as a single stick. A little experimenting may help solve your issue.

ok,ill try your suggestion.

but is the ram the culprit ?,

i ask because i ran memtest86+ for 4 passes,and it didnt detect a single error.

if it is the ram then shouldnt there be atleast 1 error ?

If it were any other brand of mobo then i'd say trust memtest results. But with asus, it's not usually the ram itself that is the problem, it's usually the mobo itself that causes the issues.

I will give you an example, a friend got an asus board not long ago. It crashed and bsoded all the time. He had a single 1 gig stick of ram in it. He got a second identical stick, fitted it, no more crashes and bsods even tho the original stick is still in there.

You referred to various bits losing power - have you tried running Everest (from www.majorgeeks.com) to see if your voltages are true and stable?
If you can try another PSU I would, even if your PSU is fairly new it might have a problem.

tnx AlbertLionheart for the reply,and yes i did monitor the voltages,with a utility that asus provides and with another software called speedfan,both utilities report voltages to be normal(+5 -5 +12 and -12V).cpu voltage is default.none of the components are overclocked.all are factory settings.

regarding the psu,i had to 2 psus.my first one was from a chinese company,dont remember the name,i had this problem with that power supply.later on,suspecting the power supply,i purchased a Corsair 450W psu,which i am currently using.however,the problem still persists with the corsair psu also.therfore,i have ruled out the psu.my suspicion is on ram,motherboard,and CPU.

as RIK pointed out,on asus boards its possible that the ram/board are bad.so i have procured a 1gb stick in the past few days,and have replaced my 2x512 mb mem sticks.howeer i still do face the occassional freeze.

at this point my suspicion is more and more on the motherbard/cpu.
both are covered by warranty and ive made up my mind to send em for replacement/repair.however my concern is that they might send me the same board/cpu with an OK sticker.

so,once i recieve my replacement/repaired unit,how do i determine that the problem has been solved.since this is an intermittently occuring prob,i have not found a way of making the system freeze happen when i want it to.so how would i verify that the problem has been solved ?

is there any software that would run a benchmark and compare the results iwht a set of predefined results and check if the mem/mb/cpu is working correctly ?,please do let me know.

ps-rik & AlbertLionheart,tnx both for the replies.

The only definitive test there is is memtest for the ram really.

Had a similar problem...had to replace AMD Athlon CPU

Unfortunately, I replaced my motherboard played with my Corsair chips, different video cards, updated everything, etc. Didn't work.

Finally, I replaced my single core AMD with a dual-core (i upgraded) and the problem went away. In 20 years of being a geek I've never had to replace a CPU. Go figure....bad AMD!