Lucid's HYDRA GPU pairing technology could soon allow PC builders to incorporate multiple video cards that - hear this, ATI and Nvidia - don't have to be identical. What this potentially means, among other things, is that gamers could leverage old hardware instead of just sadly setting it aside, though paired cards must be of the same brand. HYDRA differs functionally from Nvidia's SLI and ATI's Crossfire solutions, which split rendering by sectioning off the screen and alternating frames between cards, respectively, by intelligently distributing highly specific rendering tasks between the GPUs. Instead of divvying up all the tasks equally, HYDRA will only send as many polygons or shader calls as each constituent card can handle (see right of the above pic for an example of what one of two cards might be rendering). The most irritating aspects of current twin-card configurations (well, aside from the fact that you had to buy two cards in the first place) are the high cost and disappointingly low performance gains. HYDRA, which Lucid claims could scale to up to handle four unique GPUs, could remedy both of these issues if it ever comes to market. The company says it'll be soon, but that's as specific as they're getting for now. Visual learners can check out a detailed diagram of the system below. [PcPer via Slashdot]
It says the brand needs to be the same so only either Nvidia or ATI cards. I know from experience in Vista that you can not run ATI and Nvidia drivers together at the same time; however, you can run them side by side in XP without issue. We'll have to see how this takes off and if Vista is a requirement.
I wish you luck finding a motherboard that supports four 16x PCI-E slots. Currently we are limited to 3. Current Quad-SLI is limited to the 9800GX2 cards which are two cards on a single card. So only two slots are taken.
I am running SLI'd 9800GTX on a 680i motherboard with a 8600GT allowing dual monitor output with SLI enabled. The new PhysX drivers are also defaulting processing on the 8600GT allowing that to do Physics while my SLI card are processing the graphics as fast as possible.
I have two concerns with this new system. Cards will be different speeds so syncing everything will be a pain and I'm sure it will be a major thing killing performance. Secondly, I'm concerned with the speed of read memory from the video cards and then combining it to a single output display. Using DMA should make this a non issue but we'll have to see what happens. I know the PS3 doesn't like doing GPU->Main memory transfers so I'm curious to see how a PC would handle it.