sli setups and power supplys

[Ajay]

Im so confused over power requirements

Certain wesbites have just been giving either misleading or weird results when im looking into what powersupply i need for my graphics card.

So im looking at getting 2x gigabyte windforce 670s
on gigabytes website the only information i find is 550w

so what kinda powersupply should i buy im so confused by the numbers i might just give up and buy one card :/

what do i go on is it power requirements or tdp (what the hell is tdp?)

also the stock nvidia cards say 195 watts but im looking at getting a third party card from another manufacturer

 

[MadMarc]

Im so confused over power requirements

Certain wesbites have just been giving either misleading or weird results when im looking into what powersupply i need for my graphics card.

So im looking at getting 2x gigabyte windforce 670s
on gigabytes website the only information i find is 550w

so what kinda powersupply should i buy im so confused by the numbers i might just give up and buy one card :/

For one card 550W is enough, for two a 650W should handle it, personally I'd go with a 750W though
The most important thing is that you get a good quality psu

 

[Ajay]

For one card 550W is enough, for two a 650W should handle it, personally I'd go with a 750W though
The most important thing is that you get a good quality psu

hm okay but if i get two cards @ 550w each wouldnt i need like a 1200 watt?

 

[seumasbeathan]

The card doesnt use 550w :L Even with 2 670's I wouldnt think that the whole system power usage would go above 600w tbh

 

[MadMarc]

hm okay but if i get two cards @ 550w each wouldnt i need like a 1200 watt?

No the 550w from the gigabyte website includes the rest of the rig that you only need to power once, cpu, ram, mb.... a 670 can't pull ore than 170 W from the psu

 

[Ajay]

Oh wow im so dumb, okay i got it guys thanks for the help im still a noob at this stuff. sometimes something so simple goes right over my head.

right thanks for your very quick replies

 

[CPMFW]

get the corsair ax750 if you can afford it!

 

[Josh Weston]

To see how much power a GPU can pull, look at the type of power cable that can be plugged into it.
Each 6 pin can carry 75w
Each 8 pin can carry 150w
The PCIe lane itself provides 75w

So, a card with two 6 pins could only ever draw a maximum of 225w from the PSU.

 

[seumasbeathan]

Just a quickmquestion, say you have a graphics card that pulls 225w, if you were to add an identical one in as crossfire/sli would that one pull 225w as well?

 

[Josh Weston]

Yup.
Well, that would be the maximum power draw of both cards.
In reality, the cards should never be maxing that out.

 

[seumasbeathan]

Just another question, would you say I would be safe running a 5870 and a 5850 off a CX600, im not to sure as it only had 480w on the main rail

 

[Josh Weston]

I can't say i'd do it, no.

 

[seumasbeathan]

Hmm, I can recall when I got my 5850 I put it in crossfire with my brothers 5850 and that was with an OCZ 500w powers supply and that worked fine

 

[Josh Weston]

Like I say, it probably wouldn't get to that max power draw. But, you know what we're like here - we like to play it safe. Don't want your stuff getting fried

 

[seumasbeathan]

Indeed I do not although my 5870 just isn't good enough, and I have a 5850 lying around unused so I think I would try it, I would be willing to take the risk :L

 

[S_I_N]

remember its not just about the watts its amps as well

 

[ruthless_villain]

wait until you can buy a new PSU imo, even if you are on a tight budget you best wait until you have a psu that can power it and sell the old one. power it on this and the psu might end up dying and you wont be able to sell it or use your rig for a while - and when PSUs die they tend to take stuff with them.