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The main reason for multi-GPUs decline is that single GPU performance has grown much faster than both CPUs and RAM speeds. Going multi-GPU on a high-end GPU to
by semi-extrinsic 5y ago
The main reason for multi-GPUs decline is that single GPU performance has grown much faster than both CPUs and RAM speeds.
Going multi-GPU on a high-end GPU today lets you run a AAA game at 4K with all the eye candy at 150 fps rather than 110 fps, i.e. visually undistinguishable. And at the low end, it's always better performance per dollar to buy a single higher-end card.
Of course this is all orthogonal to your point of PCIe switches. Anyone thinking about multi-GPU will buy a motherboard with at least 2 PCIe 4.0 x16 slots anyway, no switches required. You can even get motherboards with 2 PCIe 5.0 x16 slots without breaking the bank.
- wtallis 5y ago> Anyone thinking about multi-GPU will buy a motherboard with at least 2 PCIe 4.0 x16 slots anyway, no switches required. You can even get motherboards with 2 PCIe 5.0 x16 slots without breaking the bank. I'm pretty sure you're referring to motherboards that have two slots which are mechanically x16, but actually using the second slot borrows half of the lanes from the first slot, leaving you operating at x8+x8. This is not the same as having a full 48+ lane PCIe packet switch between the CPU and two slots each wired for x16, which was very common for high-end consumer motherboards in the PCIe gen2 era (eg. with NVIDIA's NF200 switch). These days, you can get 32+ lanes straight from the CPU to enable two x16 slots, but that requires stepping up to a bigger CPU socket than the mainstream consumer CPU+motherboard platforms use. And I don't think you can yet buy a motherboard with two PCIe gen5 x16 slots at any price: as far as I can tell, none of the Intel Alder Lake motherboards announced so far include PCIe switches, because such switches have been cost-prohibitive for several generations now.
- namibj 5y agoThere is probably some server platform with 2 gen5 x16 slots and some more. Also the Power10 systems from IBM hit GA very recently, but I won't expect those to be easy to get (in addition to their price).
- semi-extrinsic 5y agoYeah, you are right, I was mistaken of course. Looks like probably the Xeon Sapphire Rapids will be the first system with dual PCIe Gen5 when it's out next year. Then AMD will be a little later with Zen 4.
- namibj 5y agoOnly HEDT and server platforms offer x64_64 with 32 PCIe lanes directly from the CPU. Most of those mainboards have two mechanically x16 slots, one electrically x16 until the other is populated, at which point both are electrically x8.