Tri SLI Power and Vantage

[SimonMaltby]

Finally got my new machine all up and running.

i7 920 D0
EVGA Classified Mobo
12GB OCZ Blade RAM
3 x GTX 275 in Tri SLI
Baisc Water on the CPU Only
BeQuiet 1000w PSU

After much work I have established my 'suiside' and 'stable' overclocks.
suiside = 4.65Ghz, stable = 4.4Ghz

Now my question...
at 4.4Ghz 21x210 1.35v Vcore

These tests work perfectly and run without issue...
Prime
LinX
3DMark2006 29030
SuperPi

No when I come to Vantage the first graphics test is fine. The second test at frame 4800 ish I get a complete system crash - no BSOD just complete and instant power off. The PC will auto restart and windows does not report a bad shutdown or anything on re-boot

I have tried adjusting the voltages - without change
I have tried reducing the overclock - I only get success at stock or very near stock Bclk
I then tried switching off SLI - worked fine
Then I changed to 2 way SLI with the 3rd card sat passive and all was ok

So... I think I am suffereing from a PSU overload shutdown...and therefore need to either drop to 2 way SLI and a dedicated Physix card or get a 1200W Psu

Could I ask you guys what you think and for any suggestions.

Thanks in advance

 

[D13]

I suppose if I was recommending a psu to someone for a single 275 I would say no less than 400w so theres a good chance your psu isnt quite sufficient.

Does it ever crash during games?

 

[SimonMaltby]

Does it ever crash during games?

I suppose I should try... tbh have not got that far yet... was testing for stability prior to installing any games.

 

[neon.uk]

I suppose if I was recommending a psu to someone for a single 275 I would say no less than 400w so theres a good chance your psu isnt quite sufficient.

A 275 doesn't draw 400W. If you reccommended a PSU for a 275 system then yes 400W, but remember that includes the rest of the system. Your PSU is 1000W of quality and should handle 3x 275s, I wouldn't say that's the problem.

 

[Duran]

I suppose if I was recommending a psu to someone for a single 275 I would say no less than 400w so theres a good chance your psu isnt quite sufficient.

Does it ever crash during games?

lol so you are saying that each 275 consumes 400 watt? ridiculous... 400w for the whole system, add 2 extra cards and you never go above 800w.

your psu wattage is more than sufficient, try to take out one card though. could be faulty

 

[D13]

lol so you are saying that each 275 consumes 400 watt? ridiculous... 400w for the whole system, add 2 extra cards and you never go above 800w.

your psu wattage is more than sufficient, try to take out one card though. could be faulty

uh calm down, just making a suggestion. I dont think its that unreasonable; there are no nvidia cert psu for tri sli 285 under 1200w, and the load power draw is very similiar to 275

 

[SimonMaltby]

uh calm down, just making a suggestion. I dont think its that unreasonable; there are no nvidia cert psu for tri sli 285 under 1200w, and the load power draw is very similiar to 275

And don't forget how far i am pushing the CPU the wattage on the CPU will probably be double the 130W standard for a 920.

My estimate is that i'm using 200w to 250w per GPU at full load and then another 200 - 220w on the cpu then there is hard drives, motherboard ect. I recon 1000W is on the edge myself.

 

[SimonMaltby]

Well I have answered my own question then...

I have plugged one of the GPU's into a second PSU and now Vantage runs perfectly in Tri SLI

So either I'm putting too much load on one of the 12v rails or I need more Wattage.

 

[D13]

Well I have answered my own question then...

I have plugged one of the GPU's into a second PSU and now Vantage runs perfectly in Tri SLI

So either I'm putting too much load on one of the 12v rails or I need more Wattage.

lol 1000w not enough, you do realise mother nature cries whenever you switch your pc on

 

[SimonMaltby]

I did a bit more digging and even pulled out the BeQuiet PSU manual *Shock*
It seems that the Pci-e connectors run off only 2 12v rails - the PSU has 6 12 rails each with a max of 20A. So I was running 3 GTX275's of 12v Rails with a max of 40A.

I also noticed that the Molex and SATA connectors also have 2 12v rails with 20A each... as there is no way they will be anywhere near that load, I have diverted one of the 6pin Pci-e power slots to the Molex line.

This has also cured the issue.

So it's not that the PSU does not have enough to give... it's the distribution.

 

[Sasahara]

GTX 275 max out at 219 W X 3 657w (54.75A)

But also it's gonna be almost impossible to get all 3 gpus running at 100% in normal gaming, Furmark maybe. Even Vantage probably won't go over 90%.

CPU at the over clock in theory could use as much as 275w, but that's extremely unlikely, in real world usage the 200-220w (18A) you said is probably on the mark.

Add 60-100w for the rest and your well into the 900-1000w area.
Most of that is on the +12V.

The PSU has a max of 900w on the +12v, so it could be the problem.