Yeah it would probably speed up the CPU's ability to send rendering data to the GPU a little, but you'd have to go with at least 1600 speed RAM to see a difference. The reason being is your CPU is a bit old too. 1600 has always been the sweet spot for DDR3 though. Beyond that the speed benefit drops off quite a bit.
Note that you will have to put your MB BIOS in XMP mode to get the rated speed out of the RAM though. Otherwise it will only run at 1333, which is same as 665 btw. Your BIOS only shows one half, but it actually runs at double that speed.
The thing is though, if you can save up more or have been considering a CPU, MB, RAM upgrade, I would advise that, especially since holiday deals will be here soon.
Before you do all this, try to find the rated speed of your RAM. It usually has stickers on the side with the specs. If you can't, try setting your BIOS to XMP to see if it bumps up the RAM speed. It could be you have 1600 RAM instead of 1333 and don't realize it.
Also make SURE you read the RAM install page of your MB manual to make sure the RAM is installed in the proper slots for dual channel mode, which is faster than single channel. It also helps if the RAM is a kit of two modules that are tested to be within close frequency and timings of each other. RAM sticks sold for dual channel are matched sets, and tested that way when rated for speed.