Right, I've been asked this many times and when I look it up I get conflicting information. If you have a motherboard that supports Tri-Channel RAM (Socket 1366) and you buy 2 sets of 2 sticks of dual channel RAM and use 3 of the sticks... what happens? When I tried it a long time ago the board wasn't happy, but looking back on it the ram itself might not have liked it or been dodgy. I see a few outcomes: 1) The channels listed on the packages are just what they are intended for and will work in a tri-channel setup in tri-channel mode 2) the sticks will run in single channel mode 3) system will throw a hissy fit 4) it will be like pouring coke into a pepsi bottle and the universe will end. Anyone know for certain? What with Intel abandoning the 1366 and Tri channel RAM it's getting harder and harder to find.
any RAM is fine just buy matched timings and Voltage. The reason is #1) If the RAM is the same timings and voltage it will be fine. same model/make is preferred to avoid the 1/1000 chance it refuses to work but you should be ok. you can use different timings and speeds but it will run at the lowest sticks speed overall.
The only difference between buying an actual tri-channel kit as opposed to some other is that it comes with a guarantee from the manufacturer that those DIMMS have been tested together and will work in a tri-channel setup. The actual DIMMS are identical to any others you would buy, there is nothing special about them that enables them to work as tri-channel. As adam_bagpuss says though you must have been very unlucky to have it not work previously.
As said before you must have been very unlucky. I recently had one stick of ram go in my 1366 setup. I bought a pair of the same kind of ram and used one of these sticks to bring it back up to 3. Everything works fine and I now have a spare stick, should another go in the future.
Completely off topic but this made me think of all the "oh cr*p, did you just divide by zero" pics out there:
