there are graphics cards with dual gpus

Possibilities are endless, especially in heating department - your PC room won't need any even during the coldest winter. Although it would require to run Crysis on 6 monitors with 2560 horizontal resolution 24x7.

Welcome to XXI century

I can't even imagine the heat production and power consumption a GPU with 8-12 cores would cause.

GPU's already consist of loads of small processing units (cuda cores, shader processors, rops) maybe that's the reason?

Would be nice in the summer if it had a passive cooler. Could prob bbq on it.

ati 5870 = 1600 stream processors, ati 5970 = 3200 stream processors :)

gpus are a lot more advanced and complicated than cpus, their processing power is absolutely superior.

the cpus are at what you should be looking tbh, there, where there is still a lot of room to improve.

GPU area already 'multicore', there is 512 'cores' in the GTX580.

Maybe you could googl eyour questiosn before making threads???

As svr already said, GPU's are already massively parallel in nature, and pretty much always have been from the very start. So in order to have more GPU's on one card, you can either have mutl core GPU's, or several GPU's on one PCB.

In today's GPU's, you have have sections of logic for power management, workload distribution, for handling input data, sending/managing data in the frame buffer and for the memory bus. Other than that, a GPU is entirely parallel already. It would make no sense to replicate/mirror cores on one die, as you would have unnecessary replicates of the "control" circuitry, when all you would actually have to do is add a little more to them, and then simply add more parallel processing cores to match the performance of a "duel core" gpu AND with a smaller die area than this hypothetical dual core GPU....

Arguably it could work from an economics standpoint, as it would be less work than redesigning a whole GPU core to handle more streaming units (and would be a known entity with regards to power consumption, thermal output characteristics etc).

This argument falls down when you take into account the realities of manufacturing the die. If you have two cores per GPU, the die would be twice as large, and as such have a much higher probability of being defective AND means losing a higher percentage of the number of GPU's made per wafer as you could fit fewer GPU's on the wafer in the first place.

The workaround for this would to have each core being a physically separate die, and then having them "stapled" together (like Intel's early duel core processors) into one package. This is also expensive and the economics again argument falls down. Intel only did this in order to keep up with AMD until their one die, dual core piece was ready to be mass manufactured.

So the cheapest equivalent/solution to a "dual core" GPU would be to have two physical GPU's on one PCB (akin to Ati's X2 cards). This is convenient in several ways, as the power circuitry and RAM memory bus PCB circuit traces don't have to be redesigned for a "dual core" GPU, they merely have to be duplicated. So it's the easiest technologically, and the best solution economically :)

There are two main problems with having more than two discrete GPU's on a single card. The first being space constraints; sure you can fit several GPU dies onto a normal sized graphics card PCB, but you couldn't when you include the necessary ancillary components such as the RAM, power circuitry components (capacitors etc); let alone all the extra PCB traces required. There simply isn't space for more than two GPU dies on one standard sized card.

The second problem is that of heat management, The cooler required to manage more than two GPU's would have to be very large (more than two to three expansion slots) OR very, very expensive (something which the manufacturer is NOT willing to consider, they want to keep their profit margins up), and probably noisy. Either solution being undesirable for the end user/manufacturer. The other concern with heat is that most computer cases would struggle to deal with this, even if all the hot air was expelled out the back via slots in the expansion slots. It's just not viable :(

So in short, true "dual/quad/multi" core GPU's are nonsensical from a technological AND economical standpoint. Also, its simply not viable to have more than two discrete GPU's on one PCB due to space constraints and heat management issues :)