A:
The memory timing is indicated on the module itself and can also be determined through your BIOS, as you have seen. You may be able to improve the timing but it may cause a risk in the system's stability.
As to your 2nd concern, by which you can only use 2 x 2GB, please note that if you have a 32-bit XP, Vista, or Windows 7, you can only use a memory of 4GB or less.
Answered on 8/31/2010 by Joanna from El Segundo