# use video card as cpu

## linuxmac09

I have a spare video card that isn't being used. is it possible I can use it to speed up my machine running gentoo?

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## haarp

Only for very specific tasks (rendering, encoding movies, SETI) that have software written especially with GPUs in mind. You can not use the GPU to accelerate everyday tasks (it wouldn't make much sense anyway, since the GPU is completely different from the CPU. The GPU's strength is massively parallel computing)

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## aCOSwt

That is a GREAT idea INDEED !

However...

That is not that simple ! And... at the end of the day... you discover that...

Well... I won't tell you...

Your dream is so nice !

If you want to know more about this but... to the expense of... stop dreaming...

just google "GPU-as-CPU"

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## linuxmac09

i know its not as simple as it seems but I have heard that apple has, under the impression i got, allowed the cpu to basically use the gpu as an extension of the cpu using opengl I believe

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## Shining Arcanine

GPUs are only good for tasks that can be done with SIMD instructions. Anything else (e.g. an operating system) cannot use them.

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## eccerr0r

Another possibility is if you have an AGP video card is to steal its RAM for system memory if it's swapping and can map it into low address space... I don't know the exact details about this but it may help speed up some tasks by not needing to swap as much.

But in any case, it depends on what you want to do.  There are a lot of tasks that are done by the CPU that the GPU really has no way of assisting.  The GPU is a really specialized processor and can do only certain things, and do them fast.  It makes sense for the GPU to process OpenGL, because OpenGL is designed for graphics, and the GPU handles graphics.

The other issue being a language barrier as GPUs don't speak the same code as CPUs... At least possibly until Larabee or something comes out.

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## Shining Arcanine

 *eccerr0r wrote:*   

> Another possibility is if you have an AGP video card is to steal its RAM for system memory if it's swapping and can map it into low address space... I don't know the exact details about this but it may help speed up some tasks by not needing to swap as much.
> 
> But in any case, it depends on what you want to do.  There are a lot of tasks that are done by the CPU that the GPU really has no way of assisting.  The GPU is a really specialized processor and can do only certain things, and do them fast.  It makes sense for the GPU to process OpenGL, because OpenGL is designed for graphics, and the GPU handles graphics.
> 
> The other issue being a language barrier as GPUs don't speak the same code as CPUs... At least possibly until Larabee or something comes out.

 

Larabee was cancelled:

http://www.dailytech.com/Intel+Cancels+Larrabee+GPU+Focuses+on+Future+Graphics+Projects/article17040.htm

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## d2_racing

I know that GPU can be use to crack some WPA2 keys, but never actually see one doing that  :Razz: 

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## Shining Arcanine

 *d2_racing wrote:*   

> I know that GPU can be use to crack some WPA2 keys, but never actually see one doing that 

 

I was thinking of trying that last month toward the end of the fall semester, but a few things came up that kept me from looking into it, one of which is that the Nvidia GeForce 7900 GS in my laptop does not support CUDA, so I would be stuck programming with Brook if I were to go ahead with it.

My desktop's Nvidia GeForce 250 GTS supports CUDA, but my laptop can come with me while my desktop cannot, so cracking WPA2 keys on the road would require a link to my desktop. That requirement ruins the killer application of cracking WPA2 keys for me, which is the ability to get internet access in emergencies when you have none. :/

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## d2_racing

If you find how to do it, just post how you did it, I just want to know if it's easy or not to do that  :Razz: 

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## linuxmac09

[quote]i know its not as simple as it seems but I have heard that apple has, under the impression i got, allowed the cpu to basically use the gpu as an extension of the cpu using opengl I believe[/quote]

I was mistaken when I said open gl I was thinking open cl[/quote]

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## Shining Arcanine

 *linuxmac09 wrote:*   

>  *Quote:*   i know its not as simple as it seems but I have heard that apple has, under the impression i got, allowed the cpu to basically use the gpu as an extension of the cpu using opengl I believe 
> 
> I was mistaken when I said open gl I was thinking open cl

 

It is probably more the other way around where the CPU is acting as an extension of the GPU. The CPU can do all of the processing the GPU can do and more, but it cannot do it quickly. The GPU can do some things very fast, but it cannot do everything. I do not believe that GPUs are turing complete, although I could be wrong. Not having turing completeness would prevent them from ever operating as CPUs do, and assuming that they were turing complete, they are designed in such a way that if you were to do everything that a CPU does on them, they would lose the property of being fast and become as slow as dogs as far as CPU performance is concerned.

That could be the future of computer architecture designs, as it would make some computationally simple things absurdly slow and some computationally complex things absurdly fast, but it is not the magic bullet that you would think it is given how fast GPUs do graphics in comparison to CPUs. The idea that running graphics on a GPU makes them run quickly does not extend far past graphics.

Apple most likely is using the GPU for rendering and audio/video decoding, but aside from that, it is unlikely that they are doing anything else. The news you heard is that they probably modified their code to use OpenCL to do the things that it used to do via other interfaces like Brook or CUDA, which would make things easier for them to maintain from a developer standpoint but means absolutely nothing to you.

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