Why do these latest gen's of GPU use so much power to play video ? - Page 1
Forum section: electronics / general

author: MathWizard
author_rank: Super Contributor
timestamp: November 18, 2023, 06:13:35 pm
content: I was looking at some reviews of GPU's from this gen and last, and I was surprised how much power these top end cards use just to play video. I basically know why and how cards like RTX3080/4080/ RX6900/7900 use up around 300-400-500W and more, running some 10-15 Billion transistors, with GHz clocks.But for video playback, they also use up around 70-90W. IDK what kind of video playback that is, maybe 4k streaming or something. But that's a huge percentage of total power. So do they just not care ? Cards from from a few years ago, rated for 200-300W, playing the same thing, only used 20-30W, or down around there, even less.Is it just no one in either Nvidia or AMD bothered to "optimize" code or hardware to run video playback on less power ? Shouldn't they be able to use a small portion of the GPU for video playback ?

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 18, 2023, 08:25:53 pm
content: Nvidia RTX supports DLSS for upscaling, granted I have not seen if it's enough of an improvement over a well tuned mpv upscaler to be worth it.

author: Someone
author_rank: Super Contributor
timestamp: November 18, 2023, 09:00:48 pm
content: Quote from: MathWizard on November 18, 2023, 06:13:35 pmThere are CPUs/GPUs/SOCs with specific video decode/encode "cores", which can be anything from accelerating one small but difficult part of the process right up to completing the entire task with no other systems involved.When the video matches the supported format everything is rosy. An example being apple iOS products which would (still do?) transcode any video being copied to their internal storage greatly boosting the playback time compared to arbitrary video codec/format/parameters.How will you get hardware makers and content delivery networks to agree on formats? (and convince the user to run software that makes it all work)

author: golden_labels
author_rank: Super Contributor
timestamp: November 18, 2023, 09:27:46 pm
content: Can’t say with certainity, but let me make some guess.Did you check CPU power usage for comparison? If one moves decoding from CPU to GPU, the power consumption follows, right? Things like VP9 and H.265, or even high-resolution(1)VP8, require a lot of computation.(1)≥4K

author: Smokey
author_rank: Super Contributor
timestamp: November 18, 2023, 11:20:26 pm
content: You actually just have malware installed and your graphics card is mining Bitcoin and sending it back to North Korea :⁠-⁠)

author: nigelwright7557
author_rank: Frequent Contributor
timestamp: November 18, 2023, 11:52:07 pm
content: I use an IGPU and it just uses a few watts.I hate first person shooter games so I just tend to play simple games which don't need much power.My PC is on 12 hours a day so a graphics card at 300 watts*12 hours*365 days is 1314KWH consumption per year or about £300 GBP

author: Marco
author_rank: Super Contributor
timestamp: November 19, 2023, 12:20:06 am
content: Quote from: MathWizard on November 18, 2023, 06:13:35 pmPower gating is expensive in design and area and if customers don't generally give a shit, why bother?

author: coppice
author_rank: Super Contributor
timestamp: November 19, 2023, 12:26:07 am
content: Quote from: MathWizard on November 18, 2023, 06:13:35 pmWhere did you get those numbers? I've been measuring the consumption of my son's PC with an RTX4070 card doing a few things. That card is rated to not exceed 200W on any load. Running the heaviest games its taking somewhat less than that. Simply playing 4k videos from YouTube it wasn't taking much at all. The whole machine was drawing less than 50W from the wall.

author: MathWizard
author_rank: Super Contributor
timestamp: November 19, 2023, 04:07:23 am
content: Yeah they don;t use that much idling, that's up around 20W this gen. A few years ago it might have been 5W on some cards.I read that in latest techpowerup reviews. My 6800XT can hit over 310W in benchmarks. I might use 200W in a typical 3D game, where I can cap the FPS to 155Hz, if I was uncapped, it could get near 310W in some games I guess. Thats the numbers reported by the GPU itself.

author: coppice
author_rank: Super Contributor
timestamp: November 19, 2023, 03:26:13 pm
content: Quote from: Marco on November 19, 2023, 12:20:06 amIf you don't extensively power gate the silicon will melt. Its mostly about constraining the worst case power consumption, but when done well it leads to a very respectable idle power consumption.