Is a 750w PSU enough for ONLY powering 2 1080 Ti's?

[calvyno]

Hello,

I am planning to add 2 1080 ti's to my PC that already has 2 1080s. I have an existing 750w power supply already in this PC that powers everything fine.

I know that adding the 2 1080 ti's, I will need a second power supply. So I'm planning to get another 750w to only be used to power the 2 1080 ti's. Will it be enough since it won't be powering anything else?

 

[MauveCloud]

See this post from a couple years back:
http://www.tomshardware.com/answers/id-2324977/dangers-dual-psu.html
The part about the gpus drawing power from both the motherboard and the pci-e power connectors still applies, so they wouldn't be fully isolated to the secondary power supply.

You could consider this psu though, if your AC circuits can handle it:
http://www.corsair.com/en-us/ax1500i-digital-atx-power-supply-1500-watt-fully-modular-psu

Or run a psu calculator and see if a single top-quality 1200W unit might be enough for 4 total video cards.

 

[Bo Lee]

1080s use a lot of power. According to nVidia, a GTX1080ti uses 250 watts and they recommend at minimum 600 watt power supply if you are using a single card. So no, 750 watts is very unlikely to cut it if they are all under loads. Ideally since you are using a power supply just for them, a 1000 watt will handle it. But remember, that 250 watts is under a load. If you don't push them too hard, your 750 may work. If you start to have issues, then you would want to consider an upgrade.