The "big 3" is not the only comparitive specs to consider. The two kits are similar, but not identical. Also, a lot of motherboards require a little extra voltage to the DIMMs when occupying all slots.
Some MB's have a problem supplying enough voltage to the ram when fully populated like that. You can try bumping up the ram voltage in the bios from 1.5v to 1.6 volts and see if that makes a difference. It's worked many time before that I can attest to.
In theory RAM with identical specs should operate together, however, this is not always the case. There can be small manufacturing differences between identical products (you hear all the time about people receiving CPU's which much more thermal headroom than others of the same model, providing them with better OC capabilities). RAM is sold the way it is because the sticks are verified to work together as a set before they leave the factory.
Did you also verify both types of RAM are on the MOBO QVL? It is just a listing of officially tested RAM, other types may work, but the ones I have seen have such a large variety of types and manufacturers, to me it makes little to no sense to NOT pick one off of the QVL .
^ concur on some MBs require a slight bump in memory voltage when Oll slots are populated. Recommend going to 1.575 V as that is the max ram voltage specified by Intel Above that voids the warrentee. If 1.575 works then try backing off to 1.55.
On Ram parameters, there are many move parameters than just the normally listed 9,9,9 and it may be some of these that is giving you a problem.
If you do get it to work with all 24 gigs, MAKE sure you run prime95 for at least 4 -> 6 hours to verify stability (Ram error free).
Thanks for the quick responses guys. Sounds like maybe it's just a quirky brand thing.
I will try to bump up the voltage and see if that works. And thanks for the tip about the max. ram voltage and the warranty. I haven't messed with my BIOS much so this will be a good experiment.
Follow up question. I had already bought an extra pair of the EXACT same corsair sticks (2) 4gb before I saw the deal on the Geil sticks. When the Geil sticks didn't work I installed the extra Corsair sticks.
So now I have (4) 4gb sticks in there. All the same brand and speed, etc.
But riddle me this. My WEI Ram sub score went from 7.7 with 8gb to 7.5 with 16gb. The speed of the memory was not changed. I realize WEI is pretty sketchy in determining true performance, but shouldn't it have at least stayed the same?
I dunno the exact specifics of WEI, but I could only guess that it lowered the score because it has to address more RAM?? WEI sucks anyways lol, it truly is just for vanity! I have had scores go up and down between WEI calculations without doing anything to the system, simply re-calculating, and there is nothing to indicate I have any issues with any of my hardware.