GTX 1070 x3 PSU

[ForceX]

I was thinking of getting a third GTX 1070 for Octane rendering when I thought about my PSU.

My current PSU is 850w, looking at reviews for power draws from the wall plate for 2x GTX 1070 stressed is about 331w with the CPU sitting close to idle. That averages out to 165.5 watts per gpu w/CPU, so for 3x GTX 1070 would be around 496.5w. The CPU at idle level is fudged into the average.

I know monitoring power draw from the plug and the actual rating of the PSU are different from the listed wattage on the PSU... So

With that said for the purpose of Octane rendering would 3x GTX 1070 on a 850w PSU be sufficient?

PSU : NZXT HALE90 850w
X99 w/ 5820k. 8x8x8 setup.

[oguzbir]

I can help you with that I think..
Will edit this post When I have something to share. keep tuned in..

[ForceX]

My eyes are glued

I only ask because the cost of a new PSU would be about the same as an extra GTX 1070. Which would be more than I would be willing to spend at this point if I had to get both. I'm just trying to figure out what I can get away with

[oguzbir]

Hi, me again..

Ok. I do not know much of a power systems. There is a lot more than to it.
But I bought a AX1500i PSU few years ago. Hoping to eliminate all power issues I might face later on. I had 2 Titans and a GTX 680 4GB.
AX1500i is capable of monitoring power draw from outlet and power out (to the mainboard). Not sure how precise this is but here goes.

On top of that
I have a 3930K 3.2GHZ overclocked to 4.3
32GB ram
2x SSD's 5xHDD + some usb gadgets connected to it..
1x GTX 680 + 3x 1070 (Purchased 3rd one today)
H100i Cpu cooler with 4 fans push pull + 8 Case Fans (12 fans total)
So the computer is pretty much populated...

As promised I screengrabbed PSU monitor during GPU render.
I must say the 3x 1070 dedicated to render are Overclocked as well. So I'm trying to draw as much as I can..

The results seems like maximum power draw could be around 800 W whilst all the computer components are drawing power.
Mind you during GPU render CPU doesn't do too much work.
Assume you work on Photoshop or After Effects ( Work on system RAM and CPU ) Along with 3dsmax or any 3d app and doing GPU render on 3x1070.
In this case your power need might be around 800-900 W

But...
The most important thing about this is that you have a very high quality PSU.
The PSU I own AX1500i is supposed to have %94 Efficiency .. Take a look at the image I attach. Reports %94 - %93 efficiency...

As far as I know, Basicly the efficiency value is important because if one component can draw max eg. 180W.
Even you're not using that component, Incapable PSU's might draw that much of power even the component not in use.

If you have a lower quality PSU which it has a lower efficiency. Your system might have problems.

EDIT Just saw your PSU is NZXT HALE90 850w. it seems to be up to %90 efficient.
Bottom line so it looks like it might work. But I cant be sure.
There is another fact that in terms of power. There is a problem with random power spikes. But quality PSU can handle an amount of power spikes with no problem

Take a look at the image I attached...
Cheers,

[ForceX]

Wow that's some great data, thanks for such a fast & quality response.

I know my system would pushing it's absolute limits in regards to 3x gpu setup. Not only in power but also PCIe lanes. I think to be safe it would be best to get at least a 1kw PSU before adding an extra GPU. I would rather spend an extra 300-400ish on a PSU than risk damaging the entire rig. Like you brought up 850w @ 90% eff is just to much on the bubble for my taste.

Thank you so much for your help

[oguzbir]

No worries.

I had the same problems years ago. And I still keep my 850W quality PSU in closet.
But I ditched the idea and bought 1500W when GTX 1st gen Titans needed more power.
I couldn't but 4xTitans back then but now I'm comfortable
I'd be in your place if 1070s were back in that time.

[smicha]

Oguzbir, great points above!

I always say that investment in the best possible PSU is crucial for stability, even if entire system draws not that much power. I always buy 1600W Titanium series:
- passive fan up to certain power draw and PSU temp - no noise
- ability to connect up to 9 gpus (with extra cables) or at least 4 gpus 2x8pin with a single 8 pin cables (9 gpus 2x8pin are also possible with special converters)
- over 92% efficiency
- 10 years of warranty