Upgrading my RAM

[Naimdor]

HI!
I built my computer two and a half years ago.
Intel Quad Core i5 4670K 3.4Ghz S1150
MSI Z87-G45 GAMING
8GB (2x4GB) Crucial Balistix Sport DDR3 CL9 1600Mhz
Sapphire R9 290 TRI-X 4G OC DDR5 + BF4
SSD Samsung 840 EVO 120GB SATA III
Seagate 2T 3.5'' Sata3 Barracuda
Fractal Design Define R4 White
SeaSonic S12II-620 620W
Cooler Master Hyper 212 EVO
DELL 23'' U2312HM ULTRA Sharp IPS , PIVOT

I want to upgrade my ram to 16 gigs.
should i buy another 2x4GB? or one stick of 8GB? or 2 sticks of 8GB and remove my old ram?
which is the best option? of course the first is the cheapest, but will it work just fine?

Thanks!

 

[CountMike]

2 x 8GB would be ideal, adding same 2 x 4GB next to it followed by 2 x4GB of RAM with same characteristics as old.

 

[Naimdor]

2 x 8GB would be ideal, adding same 2 x 4GB next to it followed by 2 x4GB of RAM with same characteristics as old.

Thanks.
I didn't fully understand you, 2x8GB and remove my old sticks? or just adding it?
and if ill buy 2 x4GB of RAM with same characteristics as old will it be as good? or less?

 

[CountMike]

All new and only 2 x 8GB, for greatest compatibility (as you seem set to have 16GB). Mixing memories even with same characteristics cam lower chances of full compatibility.

 

[Naimdor]

All new and only 2 x 8GB, for greatest compatibility (as you seem set to have 16GB). Mixing memories even with same characteristics cam lower chances of full compatibility.

Ok thanks again.

So any idea what to do with my old ones?

 

[CountMike]

Sell them but try first together with old ones, just might work.