Which RAM to buy?

[RafTechSA]

Hi all.

Current Memory installed : 2 x Elpida 2GB 2Rx8 PC3-10600
Machine is Lenovo M90z
Machine Specs: Detailed specifications - ThinkCentre M90z - ZA

These are the supported memory specs for my machine:

Memory​
Supports 1GB, 2GB, 3GB, 4GB upto 10.0GB 1066/1333MHz DDR3(Double Data Rate) dual channel memory support PC3-8500 (1066MHz) memory supported PC3-10600 (1333MHz) memory supported Two 240-pin SoDIMM DDR3 SoDIMM sockets

A few questions if i may:
1. Which would be best memory spec to get from the suggested? I'm guessing the DDR3 1333MHz?
2. Anyone know any resellers who i can approach without having to search the entire Carbonite site?