4GB 1066 or 6GB 800

Unless you need more than 4GiB of memory, I'd just use the 1066 and get a modest performance boost.

i dont think 6gb is really necessary, 4gigs of high quality ram will be much better IMO.

4gb of 1066 corsair dominator, and overclock it to 1200.

http://www.newegg.com/Product/Produc...82E16820145197

1066 FTW my friend

6 gb

i depends on the application

1066 for gaming ect, but things like sony vegas and 3ds max seem to like more RAM imo.

then again im prolly one of the few that run these programs xD so go with the 1066

Well, as it turns out, I managed to get all for DIMMs in there running at DDR2 1051 or something like that (due to my fsb) at 5-5-5-15. The 800mhz DIMMs I had are G.Skill PI Black chips I got a while ago, but I could never get them to go above like 870mhz or something like that. But now with the 1066 DIMMs in there, they magically boot up at this speed and pass any stress test I throw at them.
My question is however, are 2 DIMMs better/more efficient than 4? Even though all 6GBs are pretty much at 1066, my super PI time went down a bit from when I just had the 2 DIMMs at 800mhz. Could be just because I running vista now however...

Definately the 4gb sticks!

Are the timings loser than they were at 800Mhz? The memory controller might be loosening some sub-timings because you're putting extra stress on it. That might also be the reason why the 800mhz sticks can now magically work above spec.