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General PSU Question

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December 29, 2009 6:59:42 PM

I've been having trouble with my PC randomly shutting down when under load during gaming (clean shutdown, no errors). However, i've only had it happen in Crysis/Crysis Warhead, and Dawn of War 2. I don't know much of the workings behind a PSU, so i'm not sure if it's the PSU or not. Crysis will shut down anywhere between 1 minute and 15. Dawn of War 2 will run fine in campaign mode and such, but during Last Stand which has lots of enemies, it will generally shut off after maybe about 30 minutes to an hour. Could the PSU cause such rather random intervals with shutdowns, or does this sound more like a overheating issue? Games run fine when at low settings, but that still dosn't explain if it's overheating or the PSU.

My specs according to relevance:
Asus P6T-SE Mobo
i7 920 @ 2.67
295GTX
Chieftec 750W (i don't know the exact details of this PSU)

Motherboard lays at around 50c during load, which is fine. i7 lands at about 50 - 55 under load, which should be completely fine aswell. The 295GTX is at 80 - 85c at full load, which is well within the operational limits aswell. If it was overheating, i would be surprised, hence why i am in the PSU section.

Any comments would be appreciated. Does this sound like typical PSU failure? Crysis is the heaviest game there is graphically, so if any game fails, that would be it. But DoW2 surprised me. Also, is there a way to log system details just before system shutdown, such as heat? So far, i have only been able to guess what the heat was at during shutdown by looking at the general load temps.

Thanks for any help!

More about : general psu question

a b ) Power supply
December 29, 2009 8:38:42 PM

The trouble could be your PSU. I found the Chieftec Turbo 750W specs here, click on the specs tab. The specs. show that the PSU's 12v supply has 72a evenly-divided by 4 rails, so each rail has no more than 18A to supply to your 295GTX.

I cannot find the amp requirement for that card (thanks nvidia for your help - FAIL), but I'll bet it draws more than 18a at peak.

IF you had to plug-in 2 power cables to the card, leave one of those connected and find another power cable from your PSU to use on the GPU's second power connector. Assuming the newly connected cable is on another of the 12v rails, you would supplying a max of 36a to the card, and should be good to go.

That's why I buy PSUs with only one 12v rail, cable management is difficult enough without me having to balance the PSU's load.
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a c 243 ) Power supply
December 29, 2009 9:52:33 PM

treefrog07 said:
The trouble could be your PSU. I found the Chieftec Turbo 750W specs here, click on the specs tab. The specs. show that the PSU's 12v supply has 72a evenly-divided by 4 rails, so each rail has no more than 18A to supply to your 295GTX.

I cannot find the amp requirement for that card (thanks nvidia for your help - FAIL), but I'll bet it draws more than 18a at peak.

IF you had to plug-in 2 power cables to the card, leave one of those connected and find another power cable from your PSU to use on the GPU's second power connector. Assuming the newly connected cable is on another of the 12v rails, you would supplying a max of 36a to the card, and should be good to go.

That's why I buy PSUs with only one 12v rail, cable management is difficult enough without me having to balance the PSU's load.

72 amps = 864 watts
The unit you linked to is capable of 720 watts or 60 amps combined on the 12v ( see second link below )

Here's a review of the oem unit that's used in the Turbo ( among others )
http://www.hardwaresecrets.com/article/635/8
They found that OCP was set at 29 amps per rail ( maybe it was changed for Chieftec, but I doubt it ).
I have no idea about the rail distribution, but the 850 watt big brother has 2 x 18 and 2 x 30 which leads me to believe that the 30 amp rails on it are dedicated to the pcie connectors, which leads me to believe that rails 3 and 4 of the 750 watt unit are dedicated to the pcie.
Quad rail units are typically designed this way so that the old rail balancing routine doesn't come into play.

All that said, we don't even know if this is the OP's power supply.
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a b ) Power supply
December 29, 2009 11:03:51 PM

I was having a similar problem, but it was caused by having nTune installed (nVidia performance settings), which caused the fans on my 285s not to ramp up with heat.
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a b ) Power supply
December 30, 2009 2:00:00 AM

delluser1 said:
72 amps = 864 watts
The unit you linked to is capable of 720 watts or 60 amps combined on the 12v ( see second link below )

Here's a review of the oem unit that's used in the Turbo ( among others )
http://www.hardwaresecrets.com/article/635/8
They found that OCP was set at 29 amps per rail ( maybe it was changed for Chieftec, but I doubt it ).
I have no idea about the rail distribution, but the 850 watt big brother has 2 x 18 and 2 x 30 which leads me to believe that the 30 amp rails on it are dedicated to the pcie connectors, which leads me to believe that rails 3 and 4 of the 750 watt unit are dedicated to the pcie.
Quad rail units are typically designed this way so that the old rail balancing routine doesn't come into play.

All that said, we don't even know if this is the OP's power supply.


I know, but when I googled the PSU and saw the 4 rails, I remembered that if the load distribution was unbalanced - you get a BSOD - and the 285GTX uses a lot of power. Kind of a shot in the dark, since he didn't provide the model#. Assembling a balanced, cost-effective computer system is far more challenging than most believe. I'm no longer surprised to read about problems with a several-hundred dollar system relying on a $50 PSU, but still wonder: "What are you thinking?"
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a b ) Power supply
December 30, 2009 2:13:30 AM

MagicPants said:
I was having a similar problem, but it was caused by having nTune installed (nVidia performance settings), which caused the fans on my 285s not to ramp up with heat.


Yes, but the OP said "is at 80 - 85c at full load, which is well within the operational limits aswell."
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a c 135 ) Power supply
December 30, 2009 2:14:34 AM

The 295 draws 195 watts.

I'd suggest downloading OCCT and running the CPU / GPU and PSU torture tests....look at the graphs for any anomalies. OCCT also monitors CPU and GPU temps.

http://www.ocbase.com/perestroika_en/index.php
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December 30, 2009 9:12:53 AM

I managed to take the side off my case, and discovered that it IS infact the Chieftec Turbo that was mentioned before.

http://www.hardware.info/en-US/productdb/bGRkaZiTmJLK/v...

Anyway, so what you're saying is that each cable only supplies 18 amps? There are 2 cables connected to it, and if they each supply only 18, it is not receiving enough juice. I have read the 295 requires atleast 46 (minimum) amps. Now i'm in trouble however, as i have no idea whats a good PSU. Any recommendations what to get that would satisfy my system's needs? A modular PSU is preferred.

Then again, i may be completely wrong with my assumption here, any comments?
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a b ) Power supply
December 30, 2009 9:27:48 AM

corsair hx 650/750/850
seasonic x650/750/md12d 850
antec signature 650/850 tp750/850 cp 850
xfx 650/850
ocz z series 650/850
silverstone 650-850
etasis 850

the gtx 295 draws 320 watts at max meaning it draws ~27 amps on it own at max
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December 30, 2009 9:50:03 AM

You sure? All the specifications i can find for the 295 says it requires 46 amps and 680 watt.
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a b ) Power supply
December 30, 2009 9:56:15 AM

that specification is for the whole pc with a gtx 295
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December 30, 2009 10:17:12 AM

Anyway, so we have concluded that my current PSU should be adequate, what else could it be? Dishing out a few hundred bucks for a Corsair 850 has to be justified.

In any case, i'm looking at the Corsair 850, and it only has 1 12v rail at 70 amps. Now as i said, i know almost nothing of PSUs, but does that have something to do with how many sockets it has? I'm just worried that i end up buying a PSU that doesn't have enough. 8pins, 6pins and so on, it's rather confusing. I'm already using a load, and from the speciications on the Corsair compared to my Chiefec, mine seemed to have a lot more.

Whats the chance of it being a faulty or unstable PSU?

Edit: Did a PSU test with OCCT, and my PC shutdown immediately. As far as i know, it puts all components to max usage (which my PSU should be able to handle in theory). Is this proof enough, or is OCCT untrustworthy?
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a c 243 ) Power supply
December 30, 2009 10:49:48 AM

Apocca said:

Anyway,so we have concluded that my current psu should be adequate

In any case, i'm looking at the Corsair 850, and it only has 1 12v rail at 70 amps. Now as i said, i know almost nothing of PSUs, but does that have something to do with how many sockets it has? I'm just worried that i end up buying a PSU that doesn't have enough. 8pins, 6pins and so on, it's rather confusing. I'm already using a load, and from the speciications on the Corsair compared to my Chiefec, mine seemed to have a lot more.

Whats the chance of it being a faulty or unstable PSU?

Yes, it should be.

Nothing to do with how many sockets it has, it's all about the power it can provide, which is definitely more than the Chieftec 750 ( and the Corsair has more connectors )

Like Jack said, download OCCT and run the psu test. OK see that you've done it, I'd say it's time to try another psu
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December 30, 2009 11:48:20 AM

Ok, i'm going to try the Corsair 850TX. Thanks for the help guys.

I'm just going to reformat my system and try running OCCT again just incase something was interfering. My system is rather messed up at the moment.
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December 30, 2009 3:02:16 PM

Wait, now i'm confused again. There is a TX version and a HX one. Which is best for me? The TX says it ain't modular, while the HX does.
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a b ) Power supply
December 30, 2009 4:06:55 PM

The TX is not modular, the HX is modular - newegg shows it is sold out. On the HX version you don't plug-in unused power cables, you leave them in the box - so there is less cable-clutter in your case. If you get the TX version, you'll have to "hide" the unused power leads on the TX version for good cable mgmt. On cases with top-mounted PSUs, I hide the unused cables over the DVD/RW drive. On cases with bottom-mounted PSUs, I hide unused cables between the motherboard tray and the side case panel next to the motherboard.

You save ~$70 if you are willing to hide the unused cables. If you have a small case, or just want the convenience of leaving unused power cables in the box, you pay more.
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January 2, 2010 9:28:04 PM

I tried updating to the very latest drivers, and they seem to have solved the problem. Usually i never use the completely new ones as they tend to have issues, so i always tried older ones. OCCT no longer shuts down PC during PSU test, and my fans don't go into overdrive mode anymore either in Dawn of War 2 (but somehow my GPUs still remain cool).
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a b ) Power supply
January 3, 2010 1:37:23 AM

Sounds like the updated drivers solved the original problem - true?
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January 3, 2010 8:44:04 AM

Oh damn, just realized now that i did not have SLi turned on during the last test, so it would not have fully loaded the PSU. I turned it on and tried again, and the same thing happened as always, though it did take a bit longer for it to shut down this time. Perhaps the new drivers improved some SLi performance.

So the answer is no, the drivers did not solve the problem, just a mistake on my part. I'm going to install the new PSU today, hopefully that will help.
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January 3, 2010 2:12:12 PM

I installed the new PSU, and as i started the PC smoke came out of my disc drive. I think i'm gonna stick with my old PSU, as i don't want to risk burning any other components. As far as i'm concerned, i'm just lucky it was my drive, and not the motherboard, GPU or CPU.

Thanks for the help anyway. Too bad we will never know if it truly was the PSU or not.
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a b ) Power supply
January 3, 2010 3:41:47 PM

wow which drive-the optical (dvd/cd) drive? thats wierd.
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January 3, 2010 9:34:49 PM

Here we go again, lol
Monitor shuts down randomly when playing "Good Graphic" Games right?
Had same problem, people said, PSU, MOBO, RAM got stuck with it 2 years.

Change your Graphic Card(s) if thats the case. What brand is your graphic card anyway?

Sometimes some serries in a certain brand don't come out well, you got it in a bad timing...

Answered 4 of these same problems today... I should make a thread seriously... People will waste your time saying its everything else except the GPU...

Cheers

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a c 135 ) Power supply
January 10, 2010 7:16:43 PM

Apocca said:
Wait, now i'm confused again. There is a TX version and a HX one. Which is best for me? The TX says it ain't modular, while the HX does.


There's many more differences between the TX and HX, the modularity being the least of them. The Corsair TX garners an 8.5 performance rating on jonnyguru. The Corsair HX as well as the Antec CP-850 SG-850 all get 10.0's
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