So I have one Corsair CM3X2G1333C9 DDR3 2GB RAM and I want another 2GB RAM so I can have 4GB but I can't find ram like that anymore and I don't have a LOT of money to just but a new pack so I need another 2GB RAM that I can use with that one. Different brand or something. Pls help.
P.S This is my motherboard Asus P5G41T-M LX2/GB. It only has 2 RAM places and 1 is used. So what RAM should I get?Best method is to travel to crucial.com and run the online scan...
You don't have to buy theirs but the specs you need will be provided...then you can shop accordingly.

Another option is to DLoad and read the ASUS QVL list for the RAM for that MBoard...
QVL means the RAM listed has been tested in the ASUS LABS on that board and is approved...I tried the  Crucial.com  and there wasn't even my RAM on there there only was DDR2 RAMs.Because that's what the PC can handle...
If you doubt it check the QVL list from ASUS as per suggestion.It is a DDR3 Motherboard and will only accept DDR3. If the scanner says DDR2, then the scanner is flat out incorrect.

Here is the Memory QVL list for that motherboard. If you cannot find a DIMM that is the same as the one currently installed, you should be fine to select one from that list. Bear in mind that the faster DIMM will be run at the speed of the slower DIMM, so if you get a slower DIMM you'll slow down the existing memory as well. Whether memory speed matters in terms of actually perceiving a difference is another question.I have had Crucials memory tool fail to report properly on me ( and lie )as well in the past, so I always now open the case and look at the motherboard and then look up the motherboard memory specs anymore. While crucials memory scanner is probably correct 99% of the time, this is a situation where it failed yet again.

My Biostar MCP6PB M2+ Crucials scanner claimed I had 4 memory slots for maximum of 8GB SUPPORTED at 2GB per slot and I bought 4 x 2GB sticks. When I GOT the RAM for the system, I realized that it lied to me when there were only 2 slots on this board.  The memory controller likely supported 8GB, but the motherboard only had 2 slots for a total of 4GB. I ended up RETURNING 2 of the 4 sticks.