Is my PSU holding my overclock back?

[Das kobold]

As Scotty would say "I'm giving her all shes got Captain!"

My current PSU is a Corsair 750TX powering the following system:

i7 930 @ 4.3ghz stable
2 5850s @ 1000 core / 1200 mem
1 GT 220 for Physx
Asus P6T Mobo
2 OCZ 30gb SSDs
1 Western Digital 640gb SATA
1 Samsung 500gb SATA
1 NEC DVD burner
1 Swiftech WC pump
12 assorted fans in a Antec 1200 case

I am stable at the above specs but if I push it to 4.4ghz it will stay stable in Windows at idle until I try to push the video cards or cpu to full load with a benchmark. Then it crashes.

I did some poking around on the net and found that 2 5850's in Crossfire draw about 478 watts under load, the GT 220 about 265 watts and the i7 930 about 216 watts. That adds up to about 959 watts and those are probably at stocks speeds so I would guess pushing more volts thru the hardware is going to draw more power. The rest of the system components are probably not drawing much, the SSDs are a couple of watts from what I can gather.

Is my current PCU struggling to handle this setup? I was looking at some modular PSUs from Corsair, OCZ and Antec. Any suggestions on a new PSU? Should I go above 1000 watts for future proofing?

[Bobnova]

I think you're finding total system power numbers.
A 5850 at stock clocks draws ~170w, so two draws 340, a gt220 draws very little (does it even have a power connector?), and an i7 OC'd a good distance is in the 160-200w range.
That puts you at closer to 600.

You're edging up towards your psu's limits, but i don't think you're actually there.
The thing to do would be to measure the 12v rail with a multimeter, head down to harbor freight and get one of the $2 to $7 multimeters, and stick it into one of the molex connectors. The yellow wire is 12v, the blacks are ground.

Now being very careful not to let it short out against anything, fire the system up.
You want to see 12v, 11.7 to 12.4 is ok, more or less isn't good.
Now give it a full load, and see what that voltage does.

If it takes a big hit, your PSU isn't happy with life.

[EarthDog]

Those wattage numbers you listed arent even close. Thats likely total system consumption.

The GT220 by itself is likely only 100W.
The i7 930 stock is no more than 125W. Overclocked I can see it hitting 200W.

Your current PSU should be able to handle that though with not much headroom. If you want to see if its the problem, take out that (useless) PhysX card and then test.

[jarlmaster47]

yeah no bull. I mean that gt220 is stupid. it doesnt do anything and its lucky u got the gt220 to even do anything for u since its nvidia combined with ati. ANYWAY chuck the gt220 and ur fine.

[Bobnova]

The GT220 appears to be a low power card, i can't find a TDP, but it has to be <75w as there are no power connectors.

[EarthDog]

Doesnt PCIe2.0 allow 150W to the slot?

[Bobnova]

I don't think so, i thought it was still 75w. If PCIe2 allowed more the cards wouldn't be backwards compatible.

[EarthDog]

Why not? Just b/c its 150W doesnt mean the slot A. gives it B. The card takes it.

http://www.google.com/search?sourceid=navclient&aq=2h&oq=&ie=UTF-8&rlz=1T4ADBR_enUS316US316&q=pcie+2.0+150w+slot

Contradictory info...how quickly i forget...

http://www.overclockers.com/forums/showthread.php?t=614657

[Das kobold]

I have a multimeter at home right now. I will test the 12V rail when I get home tonight. The GT 220 doesn't even require a power adapter so I am betting it isn't drawing a lot of juice.

Would it be safe to assume that if my 12v rail checks out that I am good for now without needing to upgrade the PSU?

That is of course unless I get a bug in me and want to upgrade it :)

[jarlmaster47]

if ur 12v rail is good then ur fine. 11.7-12.4V is good. higher or lower and there is a problem

[Das kobold]

OK so I hooked up the ole Fluke multimeter as suggested. At boot and in Windows it is sitting at 12.08v; if run Lynx it stays stable at 12.08v, Prime 95 might cause it spike to 12.10v when it first starts but it settles back down to 12.08v. Running a 3D app is a different story. In 3dmark 06 it is hitting about 12.13v and in Furmark it spikes up to around 12.19v.

So does that mean the 2 5850's are power hungry and need a beefier PSU?

[EarthDog]

No, you are fine. The standard is 5% fluctuation, anything more than that is out of spec. If you need more power chances are it would drop, not increase.

[Bobnova]

That's wild, didn't know that.
I'd be worried about a 150w card plugged into a 75w slot.

[EarthDog]

Why is that bob? A 150W card will have external power connectors.

[Bobnova]

Ok fine, a 140w PCIe 2.0 card that relies on the 150w from the connector.

[EarthDog]

If you have a point to this, please make it as Im just not getting it...sorry. :)

Thing is, I dont know what exactly is right or wrong myself. I offered above 2 different points of view. The entire web that apparently bricked the call of the wattage at the slot vs pciesig that is the authority on it.... I just dont know capEtan!!!

Here is a TDP list btw :)... http://www.geeks3d.com/20090618/graphics-cards-thermal-design-power-tdp-database/

I wonder if the 240 has 6pin on it as it is under the supposed spec.....yes? No? STFU? lol

[ScottinIndy]

Well if you are willing to trust Antec read this, 75w per PCI-e slot, 200 watts per each connector either 6 pin or 6+2, 17@ available per connector.

http://www.antec.com/Believe_it/PSU/index.php

Anyway, I always thought it was 75 watts through the PCI-e slot and the reason for the connectors was to supply the additional needed power, So I guess I'm also confused, Cuz I don't understand the confusion... LOL!!

[EarthDog]

Well, Im siding with PCIsig on this one...75W at the slot... it was VERY confusing what I was reading....sorry for the sidebar..

[Bobnova]

The TDP list, and trying the overclock without the GT220 involved, is the important part.

Maybe the 2.0 spec raised the amount per additional connector?
I donno.