Memory Upgrade. Can I mix 'n' match?

[Skilid]

Hi all,

Spec:

Gigabyte GA-P55M-UD2 Intel P55 (Socket 1156) DDR3 Motherboard
Intel Core i5 750 2.66Ghz (Lynnfield) (Socket LGA1156) (Overclocked to 3.4GHz)
OCZ Obsidian 4GB (2x2GB) DDR3 PC3-12800C9 Dual Channel (OCZ3OB1600LV4GK)

I want to upgrade to 8GB of RAM (or 16 if the price isn't so different).

What is my best option? Can I leave the old stuff in there and add to it, or am I better off replacing it?? Shall I try and get some of my same memory off the bay and add to what I have?

What would you recommend?

Thanks.

 

[Skilid]

Mixing RAM can work, but it can also throw up issues if the timings/latency aren't the same and it may make your overclock unstable. Trying to find an identical kit produced by a now-defunct manufacturer could be tricky (OCZ's SSD business was bought by Toshiba, the rest of the company went bankrupt).

A brand new 8GB kit is about £30 and a 16GB kit is only £65.

I have found some used memory of the same type on an auction site. I think I might go for that. If I don't win it I will probably just buy new. Thanks