Heyyy, so, I have a buddy who wants to uprade his prebuilt rig (Acer Aspire M3802 - http://www.expertreviews.co.uk/pcs/276130/acer-aspire-m...) He's already upgraded the graphics card to a decen one, so he went with a better PSU and a RAM upgrade. He was running DDR2 so I suggested some DDR3 Kingston HypeX Beast 2133Mhz (2x4). Unfortunately, I've been out of the hardware game for a few years and forgot that the notch is in a different place (CRAP!). Now he's looking to change his MOBO to fit the DDR3 and work with the current CPU and GPU that he has.
Return the RAM if at all possible. There are several problems with it.
1. LGA 775 motherboards that support DDR3 are rare - the ones that do support it have seperate sockets for DDR2 and DDR3
2. the ones that do support it tend to only have 2 DDR3 sockets, and only support 2gb DIMM's.
3. 2133mhz RAM is complete overkill (even for a modern system it's not worth the money). The RAM will run at 1066 at best in his system; that is the highest speed the memory controller on the LGA 775 platform will support
If he has less than 4gb DDR2, I suggest upgrading to that much DDR2. This is where you may run into another issue, however. If he has a 32 bit OS, he will need to get a new, 64 bit OS. A 32 bit OS can only address 4gb of total memory, so the 2gb on his video card means a 32 bit OS can only use 2gb of system memory.
Come to think of it, if the video card is still in the return period, you could return that as well and purchase the 1gb version. 2gb on the 6670 is unnecessary as well. If he has a 32 bit os, then it could use 3gb system and 1gb video without having to install a 64 bit OS.