PSU for GTX 980 Ti SLI

[michaelyum]

I am using i7 6700k (overclocked to 4.8Ghz), ASUS STRIX GTX 980 Ti (single card overclocked to 1250Mhz) and have a Corsair RMx 850w PSU. Other things are pretty standard.

I know this question has been asked and answered many times before but I want to clarify something.

The wattage suggested for this ranges from 800 to 1000w. When i use the extreme power supply calculator to estimate the wattage needed for the 980 Ti SLI set up, the answer jumped from around 700w to over 900w when I change the core clock frequency from default 1000Mhz to the 1250Mhz i am using.

Is overclocking the major factor causing such a large divergence in wattage suggestion from the different sources.

I want to keep my Corsair RMx 850w for for the time being. Would it limit the ability to overclock the GPU in SLI? Actually, I don't know if there is any way to monitor the load and stability of PSU. Is there is anything observable in case my PSU is not providing power to the GPUs?

 

[Swinginking]

The Watt's given by that is just a prediction, your milage may vary. Especially considering overclocking, while overclocking you may need to increase the amount of watts being pushed to the GPU. So the reason for the increased wattage your getting IS because of the overclock itself. However, again, it is still a prediction, if you are going for extreme overclocking use the predictions and purchase a PSU that supports a higher watts.

In regards to stability, it all varies, and it all matters on how high of an overclock you want. I think you will be fine with the Corsair RMx850w that you have now to be very honest.

Im running my 3 way SLI on a 850 Evga no problems, but I have no overclock on the GPU's

Why would you want to overclock that beast, Never-mind two of them.

 

[Dunlop0078]

I cant imagine why you would need to overclock a 980 ti sli setup, but to answer your question I dont think its going to suck that much more power especially if you dont turn up the voltages.

 

[JackNaylorPE]

We use 850 watters for stock builds and 1050 watters for water cooled highly overclocked builds. And yes, OC'ing adds a substantial amount to the PSU requirement.

As you can see here, the power limiter is at 20%. And yes, that's exactly what it means, it can now take power at 20% over its rated power.

http://www.guru3d.com/articles_pages/msi_geforce_gtx_980_ti_gaming_oc_review,35.html

You might also wanna take a peek at this link where we see the 980 Ti drawing as much as 359 watts peak (293 in gaming). You will never need to support that as an average power draw, it's the job of capacitors to even up those power spikes.

http://www.techpowerup.com/reviews/Gigabyte/GTX_980_Ti_G1_Gaming/28.html

And yes, you can monitor GPU power with afterburner. And you can monitor power draw at the wall with a kil-o-watt meter.

http://www.amazon.com/P3-P4400-Electricity-Usage-Monitor/dp/B00009MDBU

As to why you would want to OC 980 Tis, the most immediate answer that comes to mind is "because you can".


Techpowerup obtained the following fps increases over reference 980 Tis:

Gigabyte G1 131.4%
Palit Jetstream 129.7%
Asus Strix 128.4%
MSI Gaming 127.2%
Zotac Amp 127.1%
EVGA SC 123.6%

If you are playing at 4k, then it's still not enough, no 2 GPUs can currently reliably / consistently deliver 60 fps at 4k. If you are playing on a 144 / 165 Hz monitor at 1440p, the 74 average fps is perhaps a little low if your intentions are to use ULMB. So yes at 1440p, that 25-30% OC will come in handy.