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Nicholas Kong

Why do graphic intensive game use a lot of energy

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Nicholas Kong    1535
I know that the GPU and CPU plays a role. Is it necessarily because CPU needs to execute a lot of cycles per instruction(CPI)?

Does pipelining the instruction consumes less battery then?

I'm not sure if I am making any sense on this but I thought at least come up with an educated guess just to strike a discussion.

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Juliean    7068

The more you calculate, the more energy you use. If you run some ultra-low-end 2d game without capping the framerate, say at 5000 FPS, you will use jus as much energy. The only difference between a graphical intensiv game and a simpler one is when you e.g. enable VSYNC. For the game that could run at 5000 FPS, at 60 FPS CPU/GPU can idle most of the time. For the high-end game that barely runs at 60 FPS even without VSYNC, both have to work full time.

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Shane C    1368

My laptop GPU uses significantly more battery life than my laptop CPU. So whenever a game turns on, I expect battery life to plummet.

 

Think of the GPU as a more power-drawing processor than the CPU that turns off when no game or 3D eyecandy is displayed, turns on when it does.

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Agony    3452

Another contributing factor is that modern CPUs are typically data starved, because the speed of memory hasn't kept up with the speed of the processor over the years.  So every time there is a cache miss, a large fraction of the transistors in your CPU are going to be sitting there idle, while the data is fetched from main memory (or even just from a level 2 or 3 cache).  I don't know about other OSes, but Windows still reports this as 100% CPU utilization, even though it is very far from 100% transistor utilization.

 

GPUs on the other hand organize data and operations much more predictably and efficiently, and can thus keep a far larger portion of its transistors operating consistently.

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ballmar    1586

Pipelining the instructions increases the speed of your application, which ends up consuming less battery than the application, which executes longer. Maybe I didn't get your question right =)

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Chris_F    3030

Each transistor on a processor consumes power while it's active -- a certain amount while open, less while closed. There's also energy consumed in switching, but even when not in use they are draining some power.

 

Are you sure about that? I though transistors in a CMOS configuration use negligible energy when in a stable state.

Edited by Chris_F

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Shane C    1368

Basically, tablets/laptops/etc are built to have fantastic battery life in things like web browsing, but not in things like games...

 

One example of this is that I believe the Tegra 4 has an extra processor it uses when idle that is different than the quad-core, and it basically shuts off the main quad-core. This could probably almost never happen during a game.

 

Let's say a tablet has a 10 hour battery life during web-browsing and idle use...

 

It might be 7.5 hours on a CPU intensive program.

 

It might be 4.5 hours in a CPU/GPU intensive program like a game.

 

The reality is, games are hard to engineer battery life toward, so they get the short end of the stick.

Edited by Shane C

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Madhed    4095

 


Each transistor on a processor consumes power while it's active -- a certain amount while open, less while closed. There's also energy consumed in switching, but even when not in use they are draining some power.

 

Are you sure about that? I though transistors in a CMOS configuration use negligible energy when in a stable state.

 

 

Correct, most power is dissipated during switching. The negligible current while in a stable state is actually the reason CMOS is used.

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Promit    13246

 

 


Each transistor on a processor consumes power while it's active -- a certain amount while open, less while closed. There's also energy consumed in switching, but even when not in use they are draining some power.

 

Are you sure about that? I though transistors in a CMOS configuration use negligible energy when in a stable state.

 

 

Correct, most power is dissipated during switching. The negligible current while in a stable state is actually the reason CMOS is used.

 

Negligible times a billion turns out to be not all that neglible. I'm not sure how much power is lost to internal current leakage, though.

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