Latencies are the only place you'll see any real-world improvement from memory speed - the clocks really don't matter. I looked at NewEgg, and didn't see any 800 CL4, but I'm assuming the 12% really isn't a lot - I'd do it - and 505090 is right, you likely won't 'see' a lot of improvement. If you want to 'see' a system improvement, a 'gentle' overclock is your best bet - I can walk you through a, say, 20-25% increase that will not put your hardware at any risk, but will show a solid, noticeable improvement in overall speed...