PC won't boot after switching off


Mar 18, 2009
My current specs:
Asus P5Q Pro
2x2GHz DDR2 800MHz
XFX 9800gx2
Samsung 500Gb 7200rpm
PSU OCZ ModXstream 780W


I am having this problem for couple of months now. About a year ago I have upgraded to my current Graphic's and PSU on my PC, that time my motherboard was ASUS p5n-e. Everything was working fine for about 5 months, then I started to have a problem every odd now and then when I powered the PC on after powering off it wouldn't boot back on immediately. It powered up the mobo, fans started to run high rpm, harddisk ticks for about 3 seconds then it stops, no lights on the DVD drive, no sign of the output to screen (didn't even wake the screen up). I had to wait for about 15 minutes for it to boot again. This started to be every time after trying to power the PC even after some time (30 min) after powering the PC off. Then it started to happen more often when I was trying to power the PC even after it was switched off for the whole night. I tried to power on, get the same thing, fans high rpm, couple of ticks from HDD, then nothing, just fans running until I switched off. Wait 15 minutes, sometimes it boots ok, sometimes I had to repeat the exercise for like two hours to get it boot. Imagine!
After like two months it just wouldn't boot at all. After like two days of occasional sessions of switching on and off i gave up. Reseated everything..tried again..nothing... So i left only mobo and CPU, tried combinations of RAMs, 2 different HDD's to boot from, without DVD drive, tried my old Graphics and new Graphics, tried to boot with old or new PSU and possible variations and combinations of this hardware but no luck. I came to conclusion that this could be only mobo, so I changed for brand new mobo which I have currently, put the hardware in and it boots on the first go. Problem solved! So i live with it for next two months until like a week ago when I try to boot my PC in the morning and same old scenario, fans on high rpm... and nothing. Switched it off, then back on boots fine. Thought one odd time doesn't count. It happened another 4 times since and I am starting to be slightly paranoid. Extremely paranoid to be honest as I really wouldn't like to be buying a new mobo after two months of using it. If someone would have any suggestions I would be really really thankful.

Thanks for looking.


Nov 4, 2008
This could be a heat related issue. Can you check your CPU temps. Make sure that inside your computer case its been blown out and that all the fans are spinning.

Some other things that can help us are knowing are:
*what is your PSU?
*what type of thermal greese are you putting on for your heat sink and cpu? Are you making sure to put the right amount on (as little as possible to cover the surface).


I agree this appears to be heat-related. As you are checking as kubes says, look closely also at any air filters at intakes and outlets. If they are clogged with dust your air flow will be poor.

There's also the possibility that the trouble is in the PSU. Whether it's heat-related or components degraded with age, that could cause your symptoms. Can you borrow a PSU and try if for a while to see if the problem persists?


Mar 18, 2009
Hi guys, thanks for quick response and also for looking. My PSU is OCZ ModXstream 780W, only had it for about 6 months. I have tried to use the older PSU but didn't help previously, with my older mobo but in fact this mobo was probably already gone when i was trying. The problem with other PSU is that it doesn't ave 8 pin connector required for 9800gx2 so ican't really test with current configuration (with graphics).
Was considering temperature issues as this model of graphics can run extremely hot. I have installed the ASUS PC Probe II suite and started checking the Temps but the CPU seems to be running between 30 and 34 celsius while the mobo between 36 and 39 celsius. I have some cooling frame attached to both chipsets on the mobo and this is pretty hot when in operation. Not sure about the mobo temps even it is showing 39 don't know if it is checking the chipsets, not sure about the RAM temp neither but the CPU seems to be pretty cool, the fan is running stable on 907rpm. The ocz PSU has got two fans sucking the air ou of the case, I have one large side fan pushing in and one front fan also pushing in.
For the termal paste I was using thin layer of Coolmaster paste, never had any issues with this one before.
Do you think I should be looking at cooling down the case more or replacement of the PSU (I am not too keen on the second option as this will cost me fortune, the decent power supply capable of giving enough power to the this graphics is not cheap).
Thanks again for looking guys.



Aug 22, 2008
last time the same thing happened to me.. lights up green on the mobo power indicator.. fans spin and everything seems okay and then it dies..

problem for me was that there was an extra mobo standoff touching the mobo causing a short.. maybe u can check for that? what do u guys think?

It's very possible that there is a short between the motherboard and case. This could also be a RAM problem. I'd go through this checklist for more troubleshooting ideas: