separate PSU for graphics card

[wellythebelly]

I've just got hold of a power color 7990. Reviews I've read have seen a Max power draw of 500w during stress testing.

My maths work that out as 42 amps.

My current PSU is an ocz zs 650 watt. Rated power on 12v line is 48amps and 550w.

Of course this is not enough for my whole system but could I use the ocz just for my GPU and hook up a smaller PSU I have just to the rest of the system?

Gaming power consumption of the 7990 is 300w and 25amps, the ocz should be more than enough for that on it own. Is there anything I'm missing or I should consider?

Reason I'm not going to get a new PSU right now is cash flow so please no telling me to get a new bigger one if it's not needed

Thanks all

 

[i7Baby]

48A 750W is needed for a 7990 pc. Don't put the 7990 in till you've got a good psu. Get one from Tier One per - http://www.tomshardware.com/answers/id-1804779/power-supply-unit-tier-list.html#13224310

 

[wellythebelly]

Thanks for the answer, the requirements you just stated are for the whole system. I am looking at using 2 PSU's, one for GPU and another for the rest of the system.

My CPU is pulling about 130, so i estimate system power draw(excluding GPU) at about 170 watts. Take that off the reccomended 750 brings the actual card usage under 600e

 

[spdragoo]

It's going to be needed. Even when a GPU is directly connected with PCIe power cables to the PSU, the PSU doesn't turn on until the power button is pressed... and there are no motherboards out there that allow you to have 2 separate PSUs connected to the power button, let alone actually connect to the motherboard.

 

[wellythebelly]

Its easy to link up 2 PSUs in a case though, either by using an aftermarket component such as add2psu or just by using a clip between 2 points on the 24 pin connector

 

[i7Baby]

Thanks for the answer, the requirements you just stated are for the whole system. I am looking at using 2 PSU's, one for GPU and another for the rest of the system.

My CPU is pulling about 130, so i estimate system power draw(excluding GPU) at about 170 watts. Take that off the reccomended 750 brings the actual card usage under 600e

And I recommend you don't fit the 7990 till you've got a proper psu.