PSU for Dual GTX 1080

[Aggressor]

I've been scouring the web to find out if my PSU 850W is going to be enough for GTX 1080 SLI.

 

The only other noteworthy power draw in my system is the CPU and fan (about 210 combined).

 

I am getting an EVGA GTX 1080 FTW which says it has a power draw of 250 but I plan on doing a least a half decent overclock. And its at that point I have no idea how much power this would require in a dual SLI setup.

 

If you have any experience with GTX 1080 SLI esp with an overclocked after market I'd love to hear your thoughts on the power consumption and if I need to upgrade to a 1000 watt PSU.

 

[MrBucket101]

you'll be fine

[Katsunaka]

Im running an overclocked 6700k, h100 with push/pull, 4 other case fans, 2 Asus Strix 1080's and case lighting all off a AX860i currently.

 

Normally I run a AX1200i, but my 24 pin plug on it broke and Corsair is RMA'ing it right now. So I broke out my back up PSU.

 

No issues, Corsair link says at idle I'm pulling 260ish out of the wall. I do not have a separate power meter to see my actual wattage, but Link is good enough for what I need.

[Aggressor]

3 minutes ago, Katsunaka said:

Im running an overclocked 6700k, h100 with push/pull, 4 other case fans, 2 Asus Strix 1080's and case lighting all off a AX860i currently.

 

Normally I run a AX1200i, but my 24 pin plug on it broke and Corsair is RMA'ing it right now. So I broke out my back up PSU.

 

No issues, Corsair link says at idle I'm pulling 260ish out of the wall. I do not have a separate power meter to see my actual wattage, but Link is good enough for what I need.

What is the wattage on your backup?

[Katsunaka]

It says in the quote..

 

I only bought the 1200w because I originally planned on 980ti SLI, but decided to wait on Pascal before buying a new card.

My 1200w is my normal PSU.. The 860 is the backup.

[MrBucket101]

7 minutes ago, Aggressor said:

What is the wattage on your backup?

EVGA says the max power draw is 215W, but with a custom BIOS and a good overclock, you could probably push that to 350W if you're lucky. Probably 300W is a better estimate

 

Not sure how you got 210W for your CPU. Should be closer to 150W.

 

So napkin math puts you at 850W. But thats all based on you consistently pulling 350W from each card, which is EXTREMELY unlikely, especially on air

[Aggressor]

6 minutes ago, MrBucket101 said:

EVGA says the max power draw is 215W, but with a custom BIOS and a good overclock, you could probably push that to 350W if you're lucky. Probably 300W is a better estimate

 

Not sure how you got 210W for your CPU. Should be closer to 150W.

 

So napkin math puts you at 850W. But thats all based on you consistently pulling 350W from each card, which is EXTREMELY unlikely, especially on air

Yes but I fear adding hard drives would push it over the edge. I think 850 is dancing a little too close to the edge.

 

The 210 for the CPU is the 140W CPU + 70W motherboard 

[Aggressor]

14 minutes ago, Katsunaka said:

It says in the quote..

 

I only bought the 1200w because I originally planned on 980ti SLI, but decided to wait on Pascal before buying a new card.

My 1200w is my normal PSU.. The 860 is the backup.

Ahh sorry didn't see that. Thanks!

[PlayStation 2]

What 850 watt PSU?

[STRMfrmXMN]

2 hours ago, Aggressor said:

Yes but I fear adding hard drives would push it over the edge. I think 850 is dancing a little too close to the edge.

 

The 210 for the CPU is the 140W CPU + 70W motherboard 

850W is nowhere near the edge, not even fucking close. You could put four in SLI without overclocking and be Ay-OK on 850W. They're not power hungry cards.

[MrBucket101]

2 hours ago, Aggressor said:

Yes but I fear adding hard drives would push it over the edge. I think 850 is dancing a little too close to the edge.

 

The 210 for the CPU is the 140W CPU + 70W motherboard 

hard drives draw like 7W, SSD's do like 1-3W

 

How does the mobo draw 70W? it literally does nothing but help supply power to other components? 32gb of DDR4 uses 12W.

 

you're fine. The only way you'll max those cards out is if they're on water. Overclock away

[Aggressor]

16 hours ago, Katsunaka said:

It says in the quote..

 

I only bought the 1200w because I originally planned on 980ti SLI, but decided to wait on Pascal before buying a new card.

My 1200w is my normal PSU.. The 860 is the backup.

 

13 hours ago, MrBucket101 said:

hard drives draw like 7W, SSD's do like 1-3W

 

How does the mobo draw 70W? it literally does nothing but help supply power to other components? 32gb of DDR4 uses 12W.

 

you're fine. The only way you'll max those cards out is if they're on water. Overclock away

 

That shows one card OC'd at 320. Sli that's 640

 

PC part picker says  my CPU and cooler together can go up to 150. Thats 790 watts there.

 

 

Then add in the MOBO wattage of up to 70, and now I'm at 860 putting me over.

 

Not to mention the hard drives adding up to 30 more.

 

The EVGA power meter also suggested I get a 1000 watt supply

 

http://www.evga.com/power-meter/

 

Based on 2 OC'd video cards and an OC'd 5820k.

 

[MrBucket101]

@Agressor motherboards don't draw power... They literally do nothing but supply power to other devices that are connected to them. At best, maybe a couple W due to inefficiencies.

 

Here, I spec'd out your system, using 4.5GHz @ 1.29v (cause nearly every 5820k is stable at those values), 2 1080 overclocked to 1978/2705 (the clocks of that gigabyte card in your screenshot), 3 - 3.5" drives, and 12 system fans, b/c why not. 

 

Stretch the wattage even more and add 10W more for overclocking your ram. You still don't get anywhere near the limits of your PSU.

 

you are just fine

 

 

[Aggressor]

1 hour ago, MrBucket101 said:

@Agressor motherboards don't draw power... They literally do nothing but supply power to other devices that are connected to them. At best, maybe a couple W due to inefficiencies.

 

Here, I spec'd out your system, using 4.5GHz @ 1.29v (cause nearly every 5820k is stable at those values), 2 1080 overclocked to 1978/2705 (the clocks of that gigabyte card in your screenshot), 3 - 3.5" drives, and 12 system fans, b/c why not. 

 

Stretch the wattage even more and add 10W more for overclocking your ram. You still don't get anywhere near the limits of your PSU.

 

you are just fine

 

 

Well darn I had already upgraded to the 1000 watt.

 

But this was very insightful thank you!

[MrBucket101]

56 minutes ago, Aggressor said:

Well darn I had already upgraded to the 1000 watt.

 

But this was very insightful thank you!

Send it back.

 

I also just realized that the screenshot above is for quad-SLI, not 2-way. It was a bit confusing, it refers to the cards as a "set" and then checking SLI/CF calculates the power draw from 2 cards.

So if you have 3-way SLI, you have 2 sets, but only 1 checkbox checked. Super confusing.

 

I also found an updated version of the calculator I was using. This one lets you input an overvoltage percentage. I used 20% because with a fully unlocked BIOS, that is the maximum power % (going off of my 980TI)

http://outervision.com/power-supply-calculator

 

Here are the correct power draw values

 

709W

 

I was wondering why my napkin math just seemed so far off lol. 

Also, why didn't you get 4 RAM modules so you can run in quad-channel?

[Aggressor]

2 hours ago, MrBucket101 said:

Send it back.

 

I also just realized that the screenshot above is for quad-SLI, not 2-way. It was a bit confusing, it refers to the cards as a "set" and then checking SLI/CF calculates the power draw from 2 cards.

So if you have 3-way SLI, you have 2 sets, but only 1 checkbox checked. Super confusing.

 

I also found an updated version of the calculator I was using. This one lets you input an overvoltage percentage. I used 20% because with a fully unlocked BIOS, that is the maximum power % (going off of my 980TI)

http://outervision.com/power-supply-calculator

 

Here are the correct power draw values

 

709W

 

I was wondering why my napkin math just seemed so far off lol. 

Also, why didn't you get 4 RAM modules so you can run in quad-channel?

I literally left my office and went to the store to make the change before the finalized the 1000W order. So it is set back to the 850W. And I broke down and ordered the 2nd gtx 1080 and some extra storage.

 

I hope you're happy

[Aggressor]

@MrBucket101

 

What is the advantage of running quad channel? How will that affect anything?

 

I thought all that mattered would be having 16 GB of ram?

[typographie]

8 hours ago, Aggressor said:

That shows one card OC'd at 320. Sli that's 640

If that graph is to be taken literally, "system power consumption" of 320 W is the entire PC (including storage, fans, memory, everything it needs to run), not just the video card. Adding another GTX 1080 doesn't double that number. It probably ends up in the 500-ish range. I think @STRMfrmXMN has it right that 850 Watts is plenty.

 

Power consumption for the card itself looks more like this (though bear in mind this is probably at reference settings):

 

 

Source:

http://www.pcper.com/reviews/Graphics-Cards/GeForce-GTX-1080-8GB-Founders-Edition-Review-GP104-Brings-Pascal-Gamers/PC-Pe

[STRMfrmXMN]

5 minutes ago, typographie said:

If that graph is to be taken literally, "system power consumption" of 320 W is the entire PC (including storage, fans, memory, everything it needs to run), not just the video card. Adding another GTX 1080 doesn't double that number. It probably ends up in the 500-ish range. I think @STRMfrmXMN has it right that 850 Watts is plenty.

 

Power consumption for the card itself looks more like this (though bear in mind this is probably at reference settings):

 

 

Source:

http://www.pcper.com/reviews/Graphics-Cards/GeForce-GTX-1080-8GB-Founders-Edition-Review-GP104-Brings-Pascal-Gamers/PC-Pe

Guru3D calculated that each card used approximately 184W each when not overclocked. http://www.guru3d.com/articles-pages/geforce-gtx-1080-2-way-sli-review,4.html

 

So if we assume that GTX 1080s have lots of overclocking headroom - which they don't, then we can assume that it'll use maybe 250W per card overclocked, 500W for GPUs, 80W for a 4790k-ish CPU and we're good. That's still overestimating it a bit but eh

[MrBucket101]

4 hours ago, Aggressor said:

@MrBucket101

 

What is the advantage of running quad channel? How will that affect anything?

 

I thought all that mattered would be having 16 GB of ram?

just gives you more memory bandwidth/performance/etc... But it's barely noticeable IRL.

 

just thought it was strange, as most ppl with X99 platforms get 4-dimms

[typographie]

4 hours ago, Aggressor said:

What is the advantage of running quad channel? How will that affect anything?

 

I thought all that mattered would be having 16 GB of ram?

Quad-channel is double the bandwidth of dual-channel. It's more important for productivity software, but memory bandwidth can affect games slightly during times when you're CPU-limited. It won't make or break a game, but it pops up once in awhile.

 

In my opinion I don't really see any downside to it. The only thing you'd have to do differently is to get your 16 GB as a 4x4 GB kit instead of 2x8 GB, and install them in the slots your motherboard manual says to. Either option will work fine, though.

[Purgent]

My rig pulls 700w max... 5820k and heavy OC Crossfire 390s.  

 

850 is way fucking overkill.