AMDSY3D :
geofelt :
Ram is sold in kits for a reason.
A motherboard must manage all the ram using the same specs of voltage, cas and speed.
Ram from the same vendor and part number can be made up of differing manufacturing components over time.
Some motherboards can be very sensitive to this.
That is why ram vendors will NOT support ram that is not bought in one kit.
It is safer to get what you need in one kit.
Ram is cheap enough.
I suggest you buy a compatible 2 x 4gb kit and keep the old ram as a spare.
How happy would you be if the new kit did not work?
What would you do then?
I was looking for the exact same RAM but Adata stopped producing them and now there not being sold anymore. Newegg is the only area that has it but is asking $100 XD. So should I buy 1866 or 2100? My Mobo says it supports 2100OC.
What is your motherboard and cpu?
Ram speed is generally irrelevant for Intel processors.
More so for amd.
1866 is about right for intel, go faster for amd.