Tri SLI 285s?

Farkie87 · Jun 5, 2009

I am currently using a antec 1000w PSU with SLI 285s, I was thinking about buying a third 285. will my current PSU work for it? I have an i7 940.

PSU: http://www.newegg.com/Product/Product.aspx?Item=N82E16817371012&Tpk=antec 1000

Ha-Nocri · Jun 5, 2009

If it was one-railed PSU I would say yes, yes it can push 3 285's. But with 4 rails I dunno. I need some info first. What connectors are on each rail? I am guessing 2 6-pins are on 1st 12V rail, another pair of 6-pins are on 2nd rail, right? What are 3th and 4th rails used for? I can't seem to find that info. One rail should be only for CPU (4-pin and 8-pin connectors).

Also, since one 285 uses a pair of 6-pin power connectors and the PSU has "only" 2 pairs how did you plan to power supply 3th card?

Oklahoma Wolf · Jun 5, 2009

No - the combined 12V rating is too close for comfort.

Ha-Nocri · Jun 5, 2009

He would have 20A "free" for CPU and the whole system beside 3 VGA's. While not terrible it indeed isn't comfortable...

zbo · Jun 6, 2009

The combined 12V rating is 70A for that PSU. I cant find out how many amps the 285s draw but I do think its cutting it close.

Just to save some confusion, with multi rail PSUs for dont add the max amps for each rail, you use the combined 12V rating.

For this PSU each rail says it has 25A, so 4x25 = 100. However really it only has 70A which you see form the combined 12V rating .

Ha-Nocri · Jun 6, 2009

285's TDP is 205W which is 17A. Multiply it with 3 and you get 51A which leaves ~20 amps "free" like I said.

About the 25A thingy, it should mean that each rail can deliver 25A max as long as combined amperage on all 4 rails does not exceed 70A. Probably OCP happens at 25A, but I did not find any review in which it was tested, sadly.

burebista · Jun 6, 2009

One GTX 285 need 160W from PSU.

Looking at a PC P&C Silencer 910 review we see that

* nForce 790i motherboard (has high power consumption
* Core 2 Quad QX 9770 Processor (overclocked to 3.6 GHz)
* 2x GeForce GTX 295 primary (4 GPUs)
* 1x GeForce GTX 275 secondary
* 3 GB Memory DDR3 @ 1600 MHz
* Optical Drive x1
* HDD x1

Needs 700W from the wall

The reality is harsh though, with all that equipment and tweaks we just could not pass ~700 Watts load.

So I'd say that you're perfect fine with your 1kW Enhance.

LE:

Ha-Nocri said:
Probably OCP happens at 25A, but I did not find any review in which it was tested, sadly.

With his little brother Quattro 850 OCP is triggered at 32A.

Ha-Nocri · Jun 6, 2009

The question is what kind of load did they apply. But either way 160W is to be expected. NVIDIA, like other manufacturers, is always careful. With OC it could probably reach 180W or somewhat more.

burebista · Jun 6, 2009

Ha-Nocri said:
The question is what kind of load did they apply.

Guru3D said:
For our test we used several pieces of software including the Cryostasis PhysX Demo and 3Dmark Vantage which allows us to go hard on the GTX 295 (Quad SLI) AND ALSO use Physx on the additional GeForce 275.

Nothing fancy, just a game with PhysX and Vantage.

And for XBit just 3dMark06.

XBit Labs said:
the 3D load was created by means of the first SM3.0/HDR test from 3DMark06 running in a loop at 1600x1200 with 4x FSAA and 16x AF.

Tri SLI 285s?

Farkie87

Registered

Ha-Nocri

Member

Oklahoma Wolf

Senior Warranty Validity Sealed Stick Remover

Ha-Nocri

Member

zbo

Member

Ha-Nocri

Member

burebista

Member

Ha-Nocri

Member

burebista

Member

Similar threads