I just purchased a Gateway SX2800. I have read some great info here about updating he video card and I'm going to update to a ATI Radeon 4350. I figured since I was in there (even though I expect it to be tricky) I am going to add extra RAM. The system states it has 4GB DDR3 @ 800 MHz. When I am researching I continually see 1600MHz. Is this OK to use? Are there any recommendations?