Memory is back compatible. So 800 would work at a reduced speed of 667, but then when you overclock it (say to, i dunno, 740) itll be well within its limit still. and in theory handle it no problem.
Ps Use the edit button
Edit: Like this! On the crucial front that looks great. But my 800>667 point still stands.
Ps Use the edit button

Edit: Like this! On the crucial front that looks great. But my 800>667 point still stands.