While that's absolutely true, it's also a fact that a poorly laid out motherboard or one with bad connections will not run any slower. Either it is electrically "good enough" or it will be flaky and unreliable if it runs at all. It will *not* run more slowly unless you clock it at a lower speed, period. I see discussions like this crop up all the time in audiophool circles. You can instantly identify the engineers and the guys for whom the technical side is some sort of black magic.
As others have stated, there will likely be performance differences from one board to another, but they will be due to firmware and clock speed variation, nothing relating to whether the CPU is in a socket or not. Likewise the speed of the RAM has no impact whatsoever on performance. Either it's fast enough to perform reliably at the speed it's being clocked at, or it will cause the system to be flaky.