Dual 970s

[Afranqui]

Hey guys, I have read the pinned forum at the top of the page and I still have a few question. I have a Corsair CX 750M in my system with a 4790k 2 drives, an H60, and the usual amount of peripherals. The forum said that you need a minimum of 700 watts for 2 970s. Should I look into getting a bigger power supply? I do not plan on doing overclocking. If you have any recommendations on PSUs that would be great too.

 

Thanks guys!

[don_svetlio]

[alexhelvetica]

Get a better PSU, that one is nasty!

I would also aim for 800w+

[Mew]

You could probably get away with a quality 550w if you're running a reference board 970 as they only consume almost 200w each when overclocked (at least that's what the bios would allow).

[don_svetlio]

You could probably get away with a quality 550w if you're running a reference board 970 as they only consume almost 200w each when overclocked (at least that's what the bios would allow).

550W would power the cards but you still have to power the CPU, SSD, HDD, RAM, fans and provide a buffer for spikes.

[ThinkWithPortals]

-snip-

Was waiting to see how long it took for that vid to be linked, lol

Anyway, that PSU is not suited for that. Get an EVGA G2/XFX XTR/Antec High Current Gamer/Seasonic anything and I'd shoot for 850W, but 750W should suffice

[ThinkWithPortals]

You could probably get away with a quality 550w if you're running a reference board 970 as they only consume almost 200w each when overclocked (at least that's what the bios would allow).

He's talking about 2 in SLI, no way a 550W would cover that

[Whorax]

Get a better PSU, that one is nasty!

I would also aim for 800w+

You absolutely do not need 800W for SLI 970s. You also don't want a CX PSU. I would get an EVGA G2 750W.

[Mew]

550W would power the cards but you still have to power the CPU, SSD, HDD, RAM, fans and provide a buffer for spikes.

 

 

He's talking about 2 in SLI, no way a 550W would cover that

 

Like I said, each reference 970 bios lets you use a max of under 200w. So 2 of them will be 400. The 4790k is rated at a tdp of 88w (let's just assume that that's the power consumption rather than thermal output). That sill leaves you plenty of room for everything else, provided it is a quality power supply. Of course, a higher wattage psu wouldn't hurt and would also be better as it will run more efficiently (preferably at the 50% load for max efficiency).

[Afranqui]

Thanks everyone!

[don_svetlio]

Like I said, each reference 970 bios lets you use a max of under 200w. So 2 of them will be 400. The 4790k is rated at a tdp of 88w (let's just assume that that's the power consumption rather than thermal output). That sill leaves you plenty of room for everything else, provided it is a quality power supply. Of course, a higher wattage psu wouldn't hurt and would also be better as it will run more efficiently (preferably at the 50% load for max efficiency).

180W is where the 970 starts at stock clocks - and it goes up to 230W with maxed power target.

[ThinkWithPortals]

Like I said, each reference 970 bios lets you use a max of under 200w. So 2 of them will be 400. The 4790k is rated at a tdp of 88w (let's just assume that that's the power consumption rather than thermal output). That sill leaves you plenty of room for everything else, provided it is a quality power supply. Of course, a higher wattage psu wouldn't hurt and would also be better as it will run more efficiently (preferably at the 50% load for max efficiency).

62 watts is not able to sustain all other components in a system. Not comfortably or with any amount of headroom at all at least.

[Mew]

180W is where the 970 starts at stock clocks - and it goes up to 230W with maxed power target.

 

NVidia rates the card at 145w. I'd rather use EVGA's rather heavily overclocked cards as a reference though, and those are rated at 170w and with max power limit (110%), that would be 187.

[don_svetlio]

NVidia rates the card at 145w. I'd rather use EVGA's rather heavily overclocked cards as a reference though, and those are rated at 170w and with max power limit (110%), that would be 187.

That's TDP - not power consumption. Not the same

[Mew]

62 watts is not able to sustain all other components in a system. Not comfortably or with any amount of headroom at all at least.

 

It really depends and I think you're kinda underestimating a quality power supply that can output more than the rated power and that's with you stressing every component in your system.

[don_svetlio]

It really depends and I think you're kinda underestimating a quality power supply that can output more than the rated power and that's with you stressing every component in your system.

Overloading works for short periods but not for hours - my PSU can overload to 850W but it can't hold that draw for several hours like a typical gaming session.

[Mew]

That's TDP - not power consumption. Not the same

 

It corresponds to the power limit that's available in the bios (6pin + 6pin + pcie lane).

[TheCaptain53]

This makes me laugh every time I see it. :')

[don_svetlio]

It corresponds to the power limit that's available in the bios (6pin + 6pin + pcie lane).

6+6+PCIe can output 250W

[Mew]

6+6+PCIe can output 250W

 

But the values in the 970 bios, at least in my 970sc acx2.0 is a combined 170w, and 187w for 110%. I can't remember the exact values as I'm not at home, but the stock bios is limited to about 60w on each 6 pin and 70w on the pcie lane for the 110% power limit or something like that. You have to manually go into the bios to raise the power coming from the 6pins to get any reasonable overclocks.

 

And like I said earlier, of course it's better to go with a higher wattage, but if you're in a pinch, a high quality psu around the 550-600w range can do the job.

[don_svetlio]

But the values in the 970 bios, at least in my 970sc acx2.0 is a combined 170w, and 187w for 110%. I can't remember the exact values as I'm not at home, but the stock bios is limited to about 60w on each 6 pin and 70w on the pcie lane for the 110% power limit or something like that. You have to manually go into the bios to raise the power coming from the 6pins to get any reasonable overclocks.

6-pins are generally about  75W-ish and the PCIe is also around that much so you could squeeze out 250W if you raised the power limit to the max (+20% in AB) but it's ill advised. Though you can draw 1300W off of 2x8-pin and 1x6-pin on LN2.

[Mew]

6-pins are generally about  75W-ish and the PCIe is also around that much so you could squeeze out 250W if you raised the power limit to the max (+20% in AB) but it's ill advised. Though you can draw 1300W off of 2x8-pin and 1x6-pin on LN2.

 

I know that 6pins can do 75w safely, and some newer powersupplies can do 150w from the 6pins as the extra 2 pins in the 8pin are just ground pins. But like I said, my 970 out of the box, has really low power limits (170w at 100%, 187 at the max of 110%) because of the bios. And because of how high the clocks are on the overclocked EVGA cards, they're a good indicator of average power draw of 970s that you can buy because they only draw as much power as they need.

 

Edit: Anyways, I'm done. The OP has already thanked us for the help.

 

Edit2: Decided to do some research rather than mindlessly looking at NVidia propaganda. A system running 970 sli uses 439 watts.

http://www.guru3d.com/articles_pages/geforce_gtx_970_sli_review,4.html

[alexhelvetica]

You absolutely do not need 800W for SLI 970s. You also don't want a CX PSU. I would get an EVGA G2 750W.

Aim for higher than what you need.

You can reuse your PSU, it doesn't have to only last one build cycle.

[STRMfrmXMN]

650-750W is ideal for 970 SLI. Go with an EVGA B2/GS/G2 of that wattage and you should be good.