Troubles upgrading Z68XP-UD3 to 24GB of Ram

[JaceLightning]

I have an Intel i7 2600K running on a Z68XP-UD3. I originally had two 4GB Corsair Vengeance Blue 1600MHz DDR3 RAM modules in my system and I bought two 8GB Corsair Vengeance 1600MHz DDR3 RAM modules to add to it for a total of 24GB of RAM.  All sticks say 1.5V on them. However, when I put the two 8GB sticks in the DDR3_1 and DDR3_2 slots and the other two in the other slots, the computer wouldn't start. The lights inside would come on, the fans would start going, and then it simply shuts down and reboot, repeating the process until I shut it off.

I installed the PC speaker to see if I was having power issues, but no beeps. Changing locations/order of the memory modules doesn't help. Adding the 4GB one at a time doesn't help either. However, having the 8GB modules in together just by themselves works just fine, so I know all four memory modules are good (but I would much rather have 24GB of memory than 16).

I have a 750 Watt power supply which should be enough I would think. And I know this has been done before, with this brand of memory:
http://legacy.tonymacx86.com/viewtopic.php?t=66849   (my computer is very similar to this one)
http://forum.giga-byte.co.uk/index.php?topic=8699.15

Does anyone have any idea what could be wrong? Do I need to upgrade my bios version?

[JaceLightning]

Hey guys. I decided to try one more time and put the smaller memory in the 1 and 2 slots, and the bigger memory in the 3 and 4 and it worked! I guess you half to count up with the memory.

Also, I let the computer sit plugged in for a few minutes (maybe to charge the capacitor in the power supply) before starting the computer. Not sure if that did the trick, but something worked!

[Fatman]

You will be lucky to have it working properly as mixing ram kits brings a lot of issues. I had 2 sets of 6Gig corsair ram and could not run them stable on my Z68 board.
If you want to run that much ram then you need to try and get it all in the one kit.

[Dark Mantis]

Hi and welcome.

Fatman is right about it more than likely just being the fact that you are mixing up different kits of different sizes that is giving you problems. Even if you were to use all matching modules you might still hit issues with voltage as they would require a tweek to increase it because of the extra loading on the memory controller.  Using different modules is just adding another variable to the equation.

Just count yourself lucky at the moment that they are running together. It might well not last though. Unless you are working with huge graphics or audio files you won't see any performance gain from having the extra RAM anyway.