Meshuggenah wrote:The reason I was considering Xeon's, aside from the core increase, is because i7's apparently aren't compatible with dual CPU motherboards.
Correct. 2 and 4 series Xeons have an external QPI link interface which is how the CPU's communicate with each other. Be wary you aren't looking at the 1 series Xeons, which are cheaper, but you can only use 1 in a motherboard, like the "consumer" desktop chips, because they don't have an external QPI interface. The first number of the 4 digit block indicates the number of CPU's that you can have in a motherboard.
e.g.
E5-2643 v4 is a 3.4GHz 6 Core, which can be used in a pair.
E5-1680 v4 is a 3.4GHz 6 Core, which can only be used singly, regardless of how many sockets your motherboard has (and in fact may not even work in a dual/quad socket board).
Meshuggenah wrote:I'm not certain whether a single i7-6850k with 6 cores at 3.6Ghz would be enough to power 25+ clients. The other option would be to upgrade to an i7-6900 8 core CPU for a bit of a price hike but even then it'd still be 3.x clients per core.
Me neither. It depends largely on the game, and what you can do to minimise the resource requirements. You could test with what you have, test a few load points, and extrapolate. It wont be super accurate but it should provide a close enough. Just remember to overprovision. As a general rule I would be inclined to try and limit to 2 clients per true core, and even then that may be pushing it.
For a lot of games currently, the issues really get harder when you hit a lack of GPU power (well after you provide enough CPU). It is a little harder to throw more GPU's at it without having 2 or possibly 3, and then you probably don't want to SLI, which then creates the potential for
cross monitor swapping issues (although these can be solved with a couple of simple configuration steps). You did mention about SLI, but then you said 24GB GPU RAM (or VRAM as it is more commonly known). In SLI, you only get total VRAM of one GPU, not the combined total. This is for
some really non-informative reasons, which I'll quote because it is hard to spot:
Gforce SLI FAQ wrote:When I configure two graphics cards in SLI mode, do the graphics cards work together to create double the memory size?
No. In SLI mode, each graphics card uses its own frame buffer memory to render a 3D application. The operating system will report a graphics card frame buffer memory size that is found on a single graphics board.