Frame limiting in games to reduce power consumption

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CA_Steve
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Frame limiting in games to reduce power consumption

Post by CA_Steve » Sat Sep 29, 2012 8:23 am

I noticed in Guild Wars 2 there is a video option to limit frame rates to 30 or 60fps. This might be a interesting equalizer between a moderate range card and a higher powered card (why push 100+fps when you only need 60). I'm curious if anyone has tried this for GW2 or other games and what results they have seen. Post your hardware in your signature, the game you tested, and power vs framerate limit below.

I'll try it with GW2 (although I doubt I'll be able to get my 5770 to push more than 60fps :D ).

edh
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Re: Frame limiting in games to reduce power consumption

Post by edh » Sat Sep 29, 2012 2:04 pm

My understanding on this in terms of GPU temperature (easier to measure) is that vsync makes no difference. The frames are rendered the same but only afterwards in buffering before writing to the screen is vsync implemented.

There's much more info out there on this concerning temperature rather than power consumption naturally and it all seems to concur with this.

mkk
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Re: Frame limiting in games to reduce power consumption

Post by mkk » Sat Sep 29, 2012 5:27 pm

If you can bear playing at 30fps then it can have a definite effect on say a laptop running off batteries. I don't know how Guild Wars 2 does it but using a frame limit of 60fps can be a good idea together with a regular 60Hz monitor regardless of VSync. Personally I need VSync on all the time since I can't stand tearing, but experiences differ.

With some games that have a startup screen in animated 3D and no frame limit there has been instances where that has been the most demanding part of the game for the graphics card, including overheating if the cooling isn't working as it should. So some kind of frame limit tends to be a sane part of a game engine.

CA_Steve
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Re: Frame limiting in games to reduce power consumption

Post by CA_Steve » Sun Sep 30, 2012 1:43 pm

Ok, had a one day delay as my Gb-E network adapter decided it wanted to go on strike.

mkk: It's not Vsync buffering, it's the actual render rate.

Here's a first look.

Settings:
e8400 @ 3.2GHz
1080p
Animation: Low
AA: none
Environment: medium
LOD Distance: Low
Reflections: None
Textures: Medium
Render Sampling: Native
Shadows: Low
Shaders: Medium
Post-Processing: Low
Best texture filtering: off
Depth Blur: on
High-Res Character Textures: off
VSync: off

Unlimited Framerates: 205W, CPU utilization ~92%, GPU utilization ~94%
Framerate limited to 60fps: 185W, CPU 60%, GPU 50%
Framerate limited to 30fps: 155W, CPU 20-30%, GPU 28%

FRAPs logged the 2 minute runs from a keep, across a bridge, and attacked a couple of critters. With the frame limiter set to unlimited, I saw framerates from 43 to 111, eyeballed average is ~75. The 60fps limiter actually limited fps to 50 and the 30 to 25fps and they were both darn flat (which seems a little odd as I look at the frame times below).

I also logged frame times to get a feel for any wild/woolly outliers. Most of the unlimited frame times were in the 8-20ms range, the "60fps" limited were in the 15-25ms range, and the "30fps" limited were in the 30-50ms range. When I get some time, I'll upload the graphs.

In any case, the no-brainer is to set it to 60fps limiting and get 20W power savings. I'll also try the 30fps limiting and see if it's playable.

Image

Image

Das_Saunamies
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Re: Frame limiting in games to reduce power consumption

Post by Das_Saunamies » Tue Oct 02, 2012 11:40 am

Very nice, glad to see actual power consumption figures for a change!

20 W is not a lot, but it's nothing to scoff at if it can be had for basically free. I doubt one would miss those extra 20-30 FPS over 60 FPS in an MMORPG. Come to think of it, that's probably not far from what your typical frugal TFT monitor uses, so basically one software option can negate the power consumption of the monitor - I would make that trade any day.

Edit1: style edit.
Last edited by Das_Saunamies on Tue Oct 02, 2012 3:13 pm, edited 1 time in total.

CA_Steve
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Re: Frame limiting in games to reduce power consumption

Post by CA_Steve » Tue Oct 02, 2012 12:58 pm

I have two Dell G2410 monitors and they consume about 15W ea. :D

Haven't taken the time for any further tweaking. Maybe later this week.

Olaf van der Spek
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Re: Frame limiting in games to reduce power consumption

Post by Olaf van der Spek » Tue Oct 02, 2012 2:00 pm

Why don't you use vsync?

CA_Steve
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Re: Frame limiting in games to reduce power consumption

Post by CA_Steve » Tue Oct 02, 2012 2:11 pm

It's more of a "I never bothered to adjust the setting". Haven't noticed any frame tearing, so far.

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