Most recent RAM kits default to 2T as far as I know. It is set in the DRAM timings in the BIOS. I'd hate to discourage a man from buying higher performance parts lol.....I will say this if it helps: The sweet spot appears to be 1600-1866MHz. At those speeds you get the most bang for your buck. The RAM will be initially recognized at whatever the JEDEC standard is for the RAM, and I'm thinking for that RAM, it is 1333. It's not a problem to change it in the BIOS to 1866MHz or whatever speed you decide on.
Personally, I would keep the RAM I have and instead put the money towards a 128-256GB SSD......it will be loads faster than your WD 10K rpm HDD. The SSD upgrade is probably the best upgrade you can do to a system like yours.
If you want to send me a PM on here, I can walk you through changing the CR in the BIOS.