I have a board like that in my old system, too. Thankfully, because for some reason, the 16x slot wouldn't take my GPU though it was fine with my new system. Didn't ever see much difference in the games I play Thankfully.Kinda surprised that an x16 card fit in the x4 slot, they usually aren't open ended. Some boards will have the x1 slot open ended but not heard about the x4 slot.