How Many Watts You Actually Need for SLI

[Termater]

So you're thinking about going SLI in your system, you Google how many watts your power supply should be for SLI.

 

The basic responses: "No less than 850 watts" "At least 900 watts" "Thousand watts if you're overclocking"

 

Why do so many people believe you need this much power? How much you really need is a power supply that is 50 watts or more than your system pulls while under load. The way you find this out is Google: "**insert graphics card name here** power consumption". There you can see how much power your computer will truly need.

 

I currently have:

I5-4690k overclocked to 4.5GHZ.

Noctua NH-D14

5 other case fans

One SSD and one Hard Drive

TWO GTX 780's in SLI. Overclocked 100MHZ. Both the Gigabyte Windforce x3 Rev 2.0's

 

How large of a power supply people said I would need: 900 watts or more.

 

How large my power supply is: 600 Watt. Be Quiet! Power Zone PSU.

 

My power consumption has never gone over 478 watts under stress tests. My living computer is living proof that you don't need huge power supplies for SLI. At least for two way. Now AMD cards take more power I understand that, which is why I said look at power consumption charts for your specific GPU's. Bottom line is don't waste money on a huge power supply and have it being half utilized.

[Godlygamer23]

What stress tests? If you used Furmark for the GPUs, NVIDIA cards throttle back and reduce power draw. Did you stress the CPU at the same time?

[Dzzope]

I'm not surprised it's  that low on a 4790K but yea.. most people go WAY over the needs (as long as it's good quality) 600 - 700 is plenty to keep the stress and heat low.

 

For reference, this is drawn from the wall so actual output from PSU to components is a little lower

On a i7 4930k @ 4.7 with 16GB 2133, and 2 480 GB Kingston HyperX

 

Methodology:

"For this test we hooked up our power supply to a UPM power meter that will log the power consumption of the whole system twice every second. In order to stress the GPU as much as possible we used 15 minutes of Unigine Valley running on a loop while letting the card sit at a stable Windows desktop for 15 minutes to determine the peak idle power consumption. 

Please note that after extensive testing, we have found that simply plugging in a power meter to a wall outlet or UPS will NOT give you accurate power consumption numbers due to slight changes in the input voltage. Thus we use a Tripp-Lite 1800W line conditioner between the 120V outlet and the power meter. "

 

[DIV1D3]

People always overestimate GPU power draw, I got a 900W PSU with the thinking of going dual R9 290s later on, and now I realise I'd be able to do the same with the upcoming Fury XT from AMD.

[Glenwing]

So you're thinking about going SLI in your system, you Google how many watts your power supply should be for SLI.

The basic responses: "No less than 850 watts" "At least 900 watts" "Thousand watts if you're overclocking"

Why do so many people believe you need this much power? How much you really need is a power supply that is 50 watts or more than your system pulls while under load. The way you find this out is Google: "**insert graphics card name here** power consumption". There you can see how much power your computer will truly need.

I currently have:

I5-4690k overclocked to 4.5GHZ.

Noctua NH-D14

5 other case fans

One SSD and one Hard Drive

TWO GTX 780's in SLI. Overclocked 100MHZ. Both the Gigabyte Windforce x3 Rev 2.0's

How large of a power supply people said I would need: 900 watts or more.

How large my power supply is: 600 Watt. Be Quiet! Power Zone PSU.

My power consumption has never gone over 478 watts under stress tests. My living computer is living proof that you don't need huge power supplies for SLI. At least for two way. Now AMD cards take more power I understand that, which is why I said look at power consumption charts for your specific GPU's. Bottom line is don't waste money on a huge power supply and have it being half utilized.

Figured I'd chime in with my own experiences here.

I ran an i7-2600K with dual GTX 780 Ti's in SLI (overclocked but not overvolted) and under gaming load it consistently overloaded my power supply within a minute or two, a 660W SeaSonic platinum (certainly no slouch). Jury-rigging another 450W unit to power the second GPU got rid of all the problems. With an 860W power supply everything runs fine, although with an i7-3930K (130W TDP processor) and everything overclocked I can still overload even that power supply with a high gaming load. So yeah, I'd say 850W-900W is the bare minimum I'd recommend if you're using dual 250W+ TDP cards.

[Termater]

What stress tests? If you used Furmark for the GPUs, NVIDIA cards throttle back and reduce power draw. Did you stress the CPU at the same time?

Prime 95 for 100% CPU load.

Furmark for GPU's 100% load

and sometimes the Valley benchmark for GPU's

[GrimNeo]

Figured I'd chime in with my own experience here.

I ran an i7-2600K with dual GTX 780 Ti's in SLI (overclocked but not overvolted) and under gaming load it consistently overloaded my power supply within a minute or two, a 660W SeaSonic platinum (certainly no slouch). Jury-rigging another 450W unit to power the second GPU got rid of all the problems. With an 860W power supply everything runs fine, although with an i7-3930K (130W TDP processor) and everything overclocked I can still overload even that power supply with a high gaming load. So yeah, I'd say 850W-900W is the bare minimum I'd recommend if you're using dual 250W+ TDP cards.

This ^. I got a 1000w psu because once I overclock everything and all my HDD and SSD should come to 900w on my Titan X sli. Just a guess though from watching that psu watt video from Linus.

[Dzzope]

This ^. I got a 1000w psu because once I overclock everything and all my HDD and SSD should come to 900w on my Titan X sli. Just a guess though from watching that psu watt video from Linus.

More like 700 but yea, you want some head-room so as not to run it hot. (and hence, loud)

[VagabondWraith]

Figured I'd chime in with my own experience here.

I ran an i7-2600K with dual GTX 780 Ti's in SLI (overclocked but not overvolted) and under gaming load it consistently overloaded my power supply within a minute or two, a 660W SeaSonic platinum (certainly no slouch). Jury-rigging another 450W unit to power the second GPU got rid of all the problems. With an 860W power supply everything runs fine, although with an i7-3930K (130W TDP processor) and everything overclocked I can still overload even that power supply with a high gaming load. So yeah, I'd say 850W-900W is the bare minimum I'd recommend if you're using dual 250W+ TDP cards.

Just curious, would a 980 Ti SLI (OC'd) be good with my build (860W)? When I built my PC I figured to be safe than sorry, but hopefully my PSU could handle 2 250W cards.

[Glenwing]

Just curious, would a 980 Ti SLI (OC'd) be good with my build (860W)? When I built my PC I figured to be safe than sorry, but hopefully my PSU could handle 2 250W cards.

Should be about the same or less power draw than my cards, and with a 4790K you probably won't have a problem with your PSU. Same one I'm using lol.

[spwath]

For that system I would have recommended 750w, to have extra room avalible

[FellTheSky]

im just going to leave this here so you think about your words

 

[th3dud3]

I'll chime in with my recent experience...

Just measured my system with a kill a watt like device but it was rated for 3kw+ so in assume it is reliable. But even with a 20% error margin, which is quite generous. I was only pulling round 720 watt... That's 720 with the error margin... Just under 600 without.... CPU and you over clocked balls to the wall also

[dfsdfgfkjsefoiqzemnd]

It varies, the components have a lot of influence here.

My PC has slightly older hardware and with a single GTX770 it used to draw around 450W from the plug when the CPU and GPU were at 100% simultaneously.

When I added my second 770, that number rose to 670-690W. At that point I ditched my 650W PSU in favor of an 850W one (another BeQuiet, of course).

So MY computer needs more than 650W, yours may need less.

[AliveGhost13]

A 750W-850W for longevity including capacitor degradation over the years, general wear and tear etc

[Termater]

im just going to leave this here so you think about your words

Yes, you take one of the single most power hungry graphics cards made, and put them in Triple SLI you're going to be seeing high wattage rates.

[Godlygamer23]

Yes, you take one of the single most power hungry graphics cards made, and put them in Triple SLI you're going to be seeing high wattage rates.

*Crossfire.

[othertomperson]

Depends on your PC, obviously. Benchmarking a 3960X and two GTX 580s definitely pushed my powerdraw from the wall over 800W. This is what I measured. I have a 1050W power supply which I think gives sufficient overhead over this.

 

Naturally since upgrading to Maxwell maximum measured power usage has gone down to about 500W, which also works out quite nicely because that's about where a ~1000W PSU is most efficient.

[FellTheSky]

Yes, you take one of the single most power hungry graphics cards made, and put them in Triple SLI you're going to be seeing high wattage rates.

1- Its crossfire, not sli

2- Its only 2 cards. Tri X stands for the model :