various GPU's in computer running DX12

[Kaiziel]

Sooo I just upgraded to a 970 4gb, and I had a 660 2gb in the computer, and before that a 620 2gb (OEM), and just out of curiousity, when DX12 comes out could I technically have all 3 in the computer running together for what ever purposes I need or the computer needs?. Ex. 970 the master, 660 the slave, 620, the idk PhysX card? or all 3 working on display? Thank you for any input/ thoughts.

 

[jdcranke07]

No. Nvidia cards of different types do not SLI. If you had separate panels (one per card) then you could have 3 desktops technically. But they will not work together like an SLI setup would. Some AMD cards can do what you are talking about, but they will default to the performance of the least powerful card. The amount of VRAM that will be used will be also reduced to the maximum capable of the lowest performing GPU. For example, if you have AMD GPU1 with 3GB VRAM and AMD GPU2 with 1GB VRAM. IF the cards were able to work in crossfire, then the system would default to the performance of the AMD GPU2 and would only use 1GB of VRAM even though the GPU1 has 3GB. In an Nvidia setup, only cards of the same tier could work with each other. Meaning if you have two 660 GPUs or a 780 reference and a 780ti this could work, but not with the radically different GPUs you have mentioned. Also, DX12 is said to have VRAM pooling in rumors. This has NOT been confirmed by Microsoft and is a big unicorn. Meaning it will not happen until Microsoft confirms in an official announcement that it will actually pool VRAM. Until then if you have two 3GB VRAM GPUs, then you will not have 6GB of VRAM like some people claim. You will have 3GB of VRAM that the system can use. This also does apply to dual GPU cards. If the dual GPU box or ad says that it has, hypothetically, 12GB of VRAM then the system will only use 6GB of VRAM since each GPU has 6GB itself. Hope this helps.

 

[Kaiziel]

Well damn, soooo gotta figure out wat to do with these "left over" cards,thanks for clarifying for me