is it bad to install a second 2G of DDR2 with faster timings than first set?

[bitt3n]

I've got 2G (2X1G) of DDR2 running at 5-5-5-18 (I think it's crucial) and I just happened to notice I have another 2G (2X1G) of DDR2 rated for 4-4-4-15 lying around (OCZ).

If I stick the second pair of sticks in my box, am I likely to encounter any problems? Is it necessary to manually change the timings on the second pair to match the first pair in BIOS? I know sticks are supposed to match, but I'm not sure whether all 4 have to match, or each pair has to match the other member of its pair.

I could just install and try but if it's not going to work I want to sell the second pair as new in retail box rather than used.

 

[Shack70]

The memory should get clocked back to the speed of the slower memory.

 

[bitt3n]

The memory should get clocked back to the speed of the slower memory.

ok thanks.. is this something a BIOS commonly does automatically (ie if timings not set manually, clock all RAM to match slowest RAM), or will I need to set the speeds manually? fwiw the board is an abit ip35

also, am I likely to run into problems using pairs of sticks from different makers, or is this generally not a problem if the speeds are set correctly? thanks again for your help

 

[Emulex]

keep one pair in one bank and one pair in the other bank.

modern chipsets should run each bank correctly. old chipsets make sure the slowest rating is what the system is running at (use cpu-z)

 

[Blain]

Different voltage ratings would more likely cause compatibility issues than timings.

 

[Spikesoldier]

Different voltage ratings would more likely cause compatibility issues than timings.

usually for insufficient voltage. if you overvolt the lower one to the spec of the higher one, i dont think that modest overvolt would produce any adverse issues other than increased heat. this may allow you to get away with this, but from a planning standpoint its a no-no.