Which CPUs fit this board?

It uses the LGA 2011-3 socket and Intel X99 chipset, so it takes Intel Core i7 and Xeon E5 v3/v4-era processors. Check the vendor's CPU support list before buying, since not every chip is validated.

How much memory can I install?

It has DDR4 DIMM slots and supports up to 128 GB total. Registered ECC memory is common on X99 builds, but confirm module support with the seller.

Does it support two graphics cards?

No. The board is listed without multiple GPU support, so plan on a single graphics card.

Is there an M.2 slot?

Yes, it has an M.2 slot alongside SATA connections. Confirm the M.2 key and lane speed with the seller, as off-brand boards vary.

Is this a good board for a new gaming PC?

Not really. X99 and LGA 2011-3 are older platforms with no path to current CPUs, and there is no multi-GPU support. It makes more sense for a budget workstation or server build.