How much GPU can my PSU handle?

[Aquila]

My PC has a 330 W PSU and is not upgradable without either getting a new case/board & PSU or getting a PSU and trying to run it external.

It came with the GTX 760 Ti and I've since installed the GTX 970 and it works beautifully.

According to this review: The NVIDIA GeForce GTX 1080 & GTX 1070 Founders Editions Review: Kicking Off the FinFET Generation

On the first page is says the TDP of the GTX 970 is 145 W and the GTX 1070 is 150 W and the GTX 1080 is 180 W.

On the power, temperature and noise page, it has a chart that shows maximum power consupmption with the FUrMark test, which shows the GTX 970 at 303 W, the GTX 1070 at 268 W and the GTX 1080 at 318 W.

I want to know, can my system run the GTX 1070 and/or 1080? I'm confused that the TDP of the 1070 is higher than the 970 but the total W under load is lower. The 1080 seems right out because 330 W PSU with 318 W GPU means only 12 W available for everything else, seems like something will break.

There's also a heat question, because the 1070 does get about 15 C higher than the 970 I currently have.

Any tips?

 

[Guytronic]

I'd track down the current/wattage demand that your CPU requires.
I'm almost sure you'll see crashing with only 12 watts overhead.

The PSU might be able to handle things if the current output is higher on the output buss.
Good quality PSU's usually handle current demand pretty well.

I think with that highest end card your looking at a need for more power.

 

[Aquila]

Just in case I've ordered a 600W PSU. I can't put it in my case, but I can probably run it external assuming cords are long enough. I'd like to figure out the math of how much exactly my PSU can handle.

 

[Guytronic]

On most power supplies there's usually a graph on the side that shows output drop under load.

Here's the particulars for an Antec @ 650 watts:


I'd say a good quality 600 watt PSU should handle anything you're wanting to do.

Also here's a good 12volt calculator that's easy to use:
Ohm's Law Calculators and Formulas

Sounds like you'll be having some fun there

 

[iOS Gravity]

As long as you have 2 sticks of ram, and a single GPU, you'll be good with a 600W PSU.

 

[Aquila]

Yes, I have 2x8 GB RAM and 1 GPU.