I am looking to put 12 GB into an x58 system with an i7 980x CPU. I am leaning toward 1333 MHz, CL9 RAM. According to my research, Photoshop doesn't seem to benefit from higher speed, lower latency RAM, so it seems pointless to put in low-latency 2000 MHz gamer memory. Is my understanding correct?
It also seems that the x58 chipset doesn't run high speed RAM at stock speeds anyway, but rather downclocks it to 1066 or 1333 or something like that... so it seems like high speed RAM on an x58 board goes unutilized anyway.
I do believe the x58 chipset supports 1333 natively but cannot support 1600+ without overclocking.
As for the CAS Latency of the RAM, it's not a huge deal for what you're looking to do. If you're truly serious, take the money that you would have spent extra on the RAM and put it towards a quality SSD for use as a scratch disk.