Power Problem?

[ratta]

Hello all,

I recently built a new system at home. Everything seemed to be working fine but I have recently come across a problem when gaming. The PC will just shut off with no warning or error message and restart instantly. Upon restart everything works fine. This usually occurs about half an hour into the game and only happens with graphically intense games (last crash I was playing Left for Dead, but I have played games like Football Manager 2012 for hours with no problems).

I have read around on here and a number of forums and think it is most likely to be a problem of inadequate power. However I thought before changing PSU I would try to rule out any other problems first. The system sits idle at around 31 - 32C and an Intel Burn test at standard gets it up to about 67-70C.

The System:

Intel i5-2500k (stock not OC)
Arctic Cooling Freezer 7 Pro Rev.2 CPU Cooler
HD Radeon 6950
Asus P8P67
Corsair Vengance 8GB (4x2GB)
2x LG GH22NS50.AUAA 22x SATA DVDRW Drive
Western Digital Caviar 1TB SATAII 64MB Cache 3.5-inch Green Internal Hard Drive OEM


Powered by:
CiT 750W Power Supply Unit with PSU and Dual 12V Rails
http://www.amazon.co.uk/gp/product/B002Q8HFEI

My suspicion is that my problem has come from trying to save a few quid on the power supply. It may also be worth mentioning that the power supply is mounted at the base of the case (Cooler Master RC-430-KWN1 Elite 430 Midi Tower with Window - Black) which means the GPU fans might not have the airflow they would have if the power supply was at the top.

 

[FinneousPJ]

That certainly is no quality PSU. Still, could it be bad enough to cause your problems, don't know really.

 

[steven0724]

The saying goes if you buy a cheap PSU, you'll buy twice and potentially buy replacements for a few other components your PSU might take down with it when it dies (depending on how lucky you are). To be perfectly honest, I'm not sure if your PSU is bad from what you've described but it seems to be the most likely culprit. If it were me I would ax that PSU and go with something more reliable. Corsair, Seasonic or XFX are all good brands. They run pricier but in this case you definitely get what you pay for!

Here's an interesting article toms wrote a few months back:
http://www.tomshardware.com/reviews/low-cost-psu-pc-power-supply,2862-5.html

 

[jsc]

If your system runs OK with 2D apps (OS, desktop), but crashes under heavy 3D (gaming use), I would suspect the PSU regardless of size.

Here is what I suspect is happening:
The PSU generates a "Power Good" signal when the main outs come up and reach "in tolerance" values. The CPU will boot when it sees this signal. If at any time, any of the PSU outputs drop out of tolerance, the "PG" signal should go away. When this happens, it forces a hardware reset/reboot cycle.

A better PSU should fix this problem.

 

[beenthere]

If you want to objectively, accurately and scientifically determine what PSU power is required for your Vid card and PC in both watts and 12v rail amps., the forum Utility link below will show you how easy it is to calculate this information and objectively determine which PSUs are quality built, reliable PSUs that can meet your needs. Be advised that the available 12v rail amps. is just as important as the total PSU wattage. You need both to be correct.

http://www.tomshardware.com/forum/314712-28-please-read-determine-power-required

 

[ratta]

Thanks to all of you for the help. The guide on Video Card power was especially useful. The PSU should provide 40 amps across the dual 12v rails. The calculations from the guide given state around 46 amps as the output I should be aiming for. So I think its time for a new PSU. This website described what I am observing as the symptoms of a poor PSU: http://www.guru3d.com/article/radeon-6950-6970-review/11

As an aside I also noticed from one of the guides above that the video card is idling at a very high temperature (around 45C). This is due to the power supply being mounted at the base of the case near to the video card. I have installed a spare fan I had and managed to drop this down to 35C ish. Until I get the new PSU I think I will be trying to limit my use of the system.

Thanks again to all for the speedy replies

 

[hunter315]

45 C is a fine idle for a graphics card, idle temps aren't what you need to worry about, load temps are. GPUs are safe up to about 90-100 C so 45 C at idle doesn't really matter as long as its load temps stay in the safe range.


Also, CIT PSUs are crap, a 750 W unit should have about 60 A between its 12 V rails, that one has at best 40 A and likely about 36 A since you cannot simply add the rails together.