Running Same Speed, Different Latency RAM

[AspiringNovice]

:x I'm upgrading from 2 to 4 gigs of RAM and I have a question. The 2 gigs of RAM i have now are 2 1 gig modules of Corsair XMS2-6400 (800MHz) with latencies of 5-5-5-12. (CL5) I was about to buy a second pair of these when I saw the identical pair of 1 gig modules (XMS2-6400, 800MHz,) but with lower latency timings of 4-4-4-12. (CL4). So if I were to buy two more gigs of the CL4 RAM and combine it with my present 2 gigs of CL5, would this be a major problem? ANy help would be appreciated.

 

[Mondoman]

The system runs a single memory bus speed, DIMM voltage, and latency value for all installed RAM. Thus, you just have to make sure all installed RAM will work at the given set of settings. As long as you (or the system on "auto") sets the slowest (highest) value for each latency, you should be fine.

One "gotcha" to watch out for is that RAM is often sold according to manufacturer-sanctioned overclock settings that require a higher DIMM voltage than the 1.8V standard for DDR2 RAM. You can't compare speeds and latencies between different voltages (that's comparing apples to oranges), so you'll have to find out settings that work for both sets of RAM at the same voltage.
This post may help to explain: http://forumz.tomshardware.com/hardware/modules.php?name=Forums&file=viewtopic&p=1249881#1249881