Why does this 12gb RAM configuration work?

[HungryHamster99]

I've got an ASrock Fatal1ty H97 motherboard and I recently checked my RAM configuration in my motherboard manual because my brother build my PC and so I never knew anything about where everything in the PC goes. I have two 4gb sticks and two 2gb sticks, but the manual says that matching sticks should be in the same coloured slots, but my RAM are all lined up one after the other, i.e. 4,4,2,2 while the motherboard is coloured red, black, red, black. I changed them to the correct order (which I think should be 4,2,4,2) but this prevents my PC from even starting so I assume that it's wrong. Why does my RAM configuration work but when following the motherboard's manual the PC doesn't start? Thanks.

 

[cin19]

1) Unplug the power core core, open the case, remove all the RAMs. Use the jumper (CLRCMOS1) to clear the CMOS. Check the manual if you can't find it. Or remove the CMOS battery to clear the CMOS.
2) Check your RAM to see they have the same speed/timing or not. If they do not have the same speed/timing, then only install the lowest speed RAM, boot the PC. If you can, then boot into the BIOS, set up( enable) the intel XMP profile for the memory in the BIOS. Save, exit, and shut down the PC.
3) Install other set of RAM, reboot the PC.
4) If you still can't boot the PC in 4,2,4,2 format, you should ask someone, or your brother for help, try to change the RAM voltage in the BIOS something like that. Or just use 8GB, or 12GB in 4,4,2, 2.

 

[kgt1182]

This is because of dual channel RAM specifications.
Lets arrange them in Red and Black channels. Now if you only have 1 pair of RAM sticks then you should put them in the same coloured slots. However you have two different pairs, so its better to put them where both channels have equal amounts of RAM.

Its even more important that each channel have the same amount of RAM.

Example:
Configuration A- 4,4,2,2
Sum up the RAM amounts
Here you have
Red Channel -> 4 + 2 = 6GB
Black Channel -> 4 + 2 = 6GB

Configuration B- 4,2,4,2
Red Channel -> 4 + 4 = 8GB
Black Channel -> 2 + 2 = 4GB
This would not work as the amount of RAM in the channels do not match, even if the RAM brands are the same.

The motherboard manual expects that most users buy RAM of the same capacity, and hence state same sticks should be in the same coloured slots.