Mixed timings causing problems?

[conorvansmack]

I'm almost certain that I have figured out a problem that I created. I have an OCZ2RPR800C44GK kit (2 x 2GB, 4-4-4-15 @ 2.1v) installed in my Asus P5Q-E w/E8400. Nothing is overclocked. I added an OCZ2RPR8004GK kit (2 x 2GB, 5-5-5-18 @ 1.8v) and started to run into problems and was unable to boot into Windows (Win7 x64). I was unable to make any BIOS changes that would work, so I removed the 5-5-5-18 kit and things went back to normal. Are there BIOS settings that I can change, or am I better off buying another OCZ2RPR800C44GK kit?
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[IGemini]

If using two sets of RAM with different specs, you need to set the BIOS to run the memory by whichever timings & voltage are lower before installing a second set. Make sure your current RAM can boot at 5-5-5-18@1.8v before installing the new stuff, I'm not quite sure how significant going from CAS 4 -> 5 would affect how much less voltage that RAM needs. A program like CPU-Z should pull what JEDEC timings it could use at 1.8v.

 

[conorvansmack]

I appreciate the advice. I was able to find another matching set of the faster pair in FS/T. Looks like I'll be selling the 5-5-5-18 soon.

 

[mfenn]

The voltages are your problem, not the timings. A 2.1V RAM isn't gonna run at 1.8V and a 1.8V kit might be feeling the heat at 2.1V

 

[conorvansmack]

I had a feeling it was that and not the timings. I figured the board would "step down" to the slower pair.

 

[mfenn]

I had a feeling it was that and not the timings. I figured the board would "step down" to the slower pair.

Yeah, you are correct. Matching timings isn't really a problem because it's easy to tell the memory to go take a breather for a few cycles!