Power Supply Power limiting GPU

[Saltvann]

What are your opinions on power limiting gpus? Is it a valid option to reduce power consumption and noise while still getting good performance?

I got interested after I saw the tomshardware review were they reduced the power consumption to 65w. Also after Josh tested the 65w processor and gtx 1060 in the S4 Mini, which is the case I am hoping to buy.

So I am wondering what are the downsides of power limiting a gpu (without reducing clock and memory speed)? Or would simply reducing clocks be a better approach.

 

[hardcore_gamer]

Power limiting is actually done by underclocking the GPU. You can't reduce power consumption without reducing the performance. Since more GPU cores + lower clock frequency combination is typically more efficient than fewer GPU cores+ higher clock frequency, it might be worth it to buy a 1060 and underclock it compared to, say, buying a GTX 1050.

 

[Saltvann]

Yes that is what I was thinking that 1060 might be quite bit more efficient than a lower end card even with a moderate to large underclock. So lets say if I wanted to reduce power consumption to 1/2 could I simply set the power target at 50% and call it a day. Or would this potentially make my card unstable?

I already have a gtx 1060 in my main rig and will surely do some testing myself. I just need some guidance to get me in the right direction.

 

[hardcore_gamer]

The easiest way to reduce the TDP is by using a BIOS editor. It can be a bit risky though. Alternatively, if your PC can handle the default GTX 1060, you can try underclocking it step by step, and monitor the power draw with a watt meter. It's a bit tricky because different games/bench marks will show different power consumption.

Edit: Either way, I don't recommend reducing the clock frequency below 65-70% of the default value. Below this point, the performance will be close to GTX 960 / GTX 1050 (per my quick calculations). That being said, a 30% underclock might be enough halve the power consumption as power Vs clock frequency is an exponential relationship.

 

[EdZ]

The easiest way to reduce power would be to use MSI Afterburner (or similar) to drop the power limit. By default, you can go down to 60% rated power without touching the card BIOS. From there, you can try messing with lowering the core voltage to eke out a bit more performance for a given power level (lower voltage = lower power, so the card can 'boost' clock speeds higher within your set power limit) without becoming unstable.

 

[hardcore_gamer]

The easiest way to reduce power would be to use MSI Afterburner (or similar) to drop the power limit.

I forgot about that option in Afterburner.

 

[Saltvann]

I did take a look at Afterburner and it seems that you can set the power limit all the way to 50%.

I am just wondering if there are any known drawbacks with this solution apart from the performance hit obviously. Will afterburner reduce clock speed automatically to keep the card under the set power limit or could the result be instability.

I will try it myself when the new build is ready however it would be nice to know if there is any potential downside to this.

 

[hardcore_gamer]

If you set a lower TDP, the GPU firmware will automatically adjust the clocks based on workload. This method has no other drawbacks except the performance hit. If you lower the core voltage, however, stability may be affected. If you're planning to lower the voltage, I'd recommend running synthetic benchmarks to stress test the GPU to make sure that it's stable.

 

[EdZ]

Note that by power-limiting, you allow the card (drivers) to atuomaticlaly reduce the voltage the GPU core is using depending on the clock speed, via a pre-set curve. This curve is already tuned to be as low a power as possible while remaining stable (as the GPU will often be in these low power states in ordinary use) so while there is a chance you could squeeze a few mV off if you happen to have 'won the silicon lottery' the amount of effort needed to do so would probably not be worth the small reward.

 

[Saltvann]

Thanks guys. Seems like this is the easiest way to go then. I will do some testing.