Megasty
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- Joined
- Mar 18, 2008
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Processor | i7 920 @ 3.6 GHz (4.0 when gaming) |
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I completely disagree in the single-die multi-core GPU thing. The whole idea of using multiple GPUs is to reduce die size. Doing dual core GPU on a single die is exactly the same as doing a double sized chip, but even worse IMO. Take into account that GPUs are already multi-processor devices, in which the cores are tied to a crossbrigde bus for communication. Look at GT200 diagram:
http://techreport.com/articles.x/14934
In the image the conections are missing, but it suffices to say they are all conected to the "same bus". A dual core GPU would be exactly the same because GPUs are already a bunch of parallel processors, but with two separate buses, so it'd need an external one and that would only add latency. What's the point of doing that? Yields are not going to be higher, as in both cases you have same number of processors and same silicon that would need to go (and work) together. In a single "core" GPU if one unit fails you can just disable it and sell it as a lower model (8800 GT, G80 GTS, HD2900GT, GTX 260...) but in a dual "core" GPU the whole core should need to be disabled or you would need to dissable another unit in the other "core" (most probably) to keep symetry. In any case you loose more than with the single "core" aproach, and you don't gain anything because the chip is the same size. In the case of CPUs multi-core does make sense because you can't cut down/dissable parts of them, except the cache, if one unit is broken you have to throw away the whole core and in the case that one of them is "defective" (it's slower, only half the cache works...) you just cut them off and sell them separately. With CPUs is a matter of "it works/ doesn't work and if it does at which speed?", with GPUs is "how many units work?".
I was thinking the same thing. Given the size of the present ATi chips, they could be combined & still retain a reasonbly sized die but the latency between the 'main' cache & 'sub' cache would be so high that they might as well leave them apart. It would be fine if they increase the bus but then you would end up with a power hungry monster. If the R800 is a multi-core then so be it but we gonna need a power plant for the thing if its not going to be just another experiment like the R600.