And as far as I know (please correct me if I'm wrong) If I would use only 2 x 2GB in dual mode - I could get 1333mhz speed (stock). But if I will use all four slots the RAM speed will automatically decreases to 1066mhz. Right?
So one of my questions is - If I had a choice to make between 4 x 2GB 1333mhz CL9 1.5v and 4 x 2GB 1066Mhz CL7 1.5v. Should I choose the slower one but with better timings? I know this sounds kinda stupid, but I'm not really sure how does this speed decrease works.
And the motherboard manual claims that it supports 4 x 1.5V DDR3 DIMM sockets. What happens if I use 4 x 1.65v DDR3 memory? Will it work?
You are probably correct about the 1066 default speed with all 4 slots filled. Be sure to check to have "memory mapping" enabled for 4 slots. If you bump up the voltage, don't go over 1.65 volts. You can try to manually adjust the memory speed to 1333 or 1600, but I wouldn't change the timings.
I got a bit short on money so I bought 2 x 2BG 1333Mhz 1.5v memory with lower timings.. At first I thought it won't be enough, because I'm using Windows 7 (64 bit) OS, but actually, it runs great I will buy another (same) kit of Ram sometime later.. I'm planning to overclock my PC when it will start to Fail on games (I hope it ain't gonna happen soon) So.., I assume that higher Ram speed might come in handy when it comes to overclocking.. But maybe I'm completely wrong (It's my first high-end pc)