Energy Efficient Graphics Processors?

An anonymous reader asks: "The trends for graphics hardware these days seems to be to draw more power and create more heat to get faster processors and push more polygons. Yet in the CPU arena chips like the Via C3 and Epia, Transmeta Crusoe and Astro, Intel Pentium M, and IBM/Motorola PowerPC (G3-5) seem to favor more power per megahertz and cooler runnings without significant performance loss. Is this just because of the nature of the CPU versus GPU? I understand a GPU die is almost entirely reserved for calculation while the CPU is only 20% of so for calculation. Or are the graphics chip makers merely refusing to innovate and take routes that would reign in out of control energy consumption because of the race for more polygons? What kind of architectural changes could be implemented to alleviate graphics card power gluttony?"

Comments

3D for laptops...

[Kris_J]

A few seconds on Google and I found nVidia's mobile offering. A few more seconds and I found this. Undoubtedly ATI has something similar.

Apples to Oranges??

[dFaust]

Ok, alot of people seem to be commenting on the comparison used here, saying the poster is comparing high-end GPUs to low-end CPUs. For one, the poster doesn't specifically target high-end GPUs... though we'll make the assumption that's what he's talking about. People have said that the CPUs are all low-end, and/or that the G5 doesn't have low power consupmtion...

I introduce this document as reference.

According to this, a PowerPC 970FX (the G5's being used in Apple's Xserves and the chip that will be in Apple's desktops this year) uses ~24.5W at 2.0ghz. So two of these are still only using half the wattage of a single Prescott chip, and obviously they can perform, too.

So yes, many of the chips he mentioned are not performance oriented, but the PowerPC 970FX certainly is, and it's safe to say it has made huge headway in power efficiency.

Re:G5?

[bhima]

The IBM PPC 970fx draws 24.5 Watts at 2 GHz.

The Opteron "HE" is classed at 55 watts (I suppose that is at 2.0 GHz or so)

The P4 extremely expensive edition dissipates 103 watts at 3.4 GHz.

So in comparison to other desktop processors it does fairly well. Now there are efficient G4 class processors coming from Motorola the MPC7447 is said to dissipate 10 watts at 1 GHz.

I am not comparing any of these processors GHz to GHz because we all know that is not an accurate method of comparison. But I think it wrong to classify the MPC7447 as a desktop processor or even a processor for a desktop replacement type laptop. But then again maybe it's because after using OS X on a G5 I'll never take Motorola seriously (for the desktop) again. That's not saying Motorola is a bad company or their chips are bad! I develop almost exclusively on them at work, but then again I am an embedded developer.

same reason P4's use put out so much heat

[TubeSteak]

"Or are the graphics chip makers merely refusing to innovate and take routes that would reign in out of control energy consumption because of the race for more polygons"

They're refusing to take routes that would reign in energy consumption.. specifically lowering clock speeds. GPU design has moved in leaps & bounds. They've been making architectural changes in order to increase performance w/out sucking down more energy, like more pipelines, wider memory bandwidth, and so on...

The biggest reason heat output keeps going up is that these gains only provide incremental benefits. To truly leverage the design changes, you have to run it as fast as it'll go ---> lots of heat.

The PowerPC isn't anything to scoff at, but if anyone could easily bump up the voltage & the multipliers, I'm sure a new G5 could be used to heat up your room in the winter.... and btw- Heat output does not increase linearly. The newer ATIs come with stock GPU & RAM voltages around 1.7 & 2.9. Unlike AMD/Intel/Nvidia/ATI *PUs, mac's aren't easily overclockable and when they are OCed they have very fine tolerances. Maybe if the powerpc chip put out a little more heat it could go faster?

Low Power GPU

[DrYak]

3 words : Tile Based Rendering

PowerVR used to make a GPU with the transistor count of a Voodoo 2 card, but with the power of GeForces 2 of its time.

These days, they are using this technology to build very low powered GPU for embed systems.

But they announced that they will soone start again to build GPU for SEGA's arcade systems.
Let's just hope they'll soon built a PC derivative of this arcade GPU.