I'm looking to buy some more RAM, as I recently noticed some problems with 4GB not being enough for Skyrim fully modded and, strangely enough, even Mass Effect 1 with mods told me I didn't have enough memory. Fortunately, RAM is currently very cheap, but I couldn't really find a comprehensive RAM article on Tom's and still had some questions after some searching on the internet.
I currently have 2x2GB of Kingston KHX1333C7D3K2/4G Memory, at a frequency of 1333Mhz and a CL of 7 (mobo: ASUS P7P55D, i5 750, not planning on OCing). Now, simply buying another identical kit to upgrade to 4x2GB would cost me €30 (~$40), but I was wondering whether an upgrade to 2x4GB would be worth it, or even to 2x4GB at a higher frequency (which would be 1600Mhz), at €50-60 (~$70-80). Is there any real performance improvement when using less kits or with increased frequency/lower latency or should I just buy another kit of 2 of the same memory I already own? I'm thinking the latter is the better option in my case, as I mostly use my machine for gaming, but I was hoping someone who knows more about this could confirm that. Thanks for your help!
It is most stable and fast to use 2X4Gb. However, if you want to use 4X2Gb all sticks have to be identical. There shouldn't be real gaming difference between 4Gb or 8Gb, however their price difference is insignificant. I use 8Gb for my 64bit OS so it is more stable and responsive.
4 x 2GB generally meant reducing speed or timings when overclocking ... this is somewhat less of an issue with SB as BCLK isn't fiddled with much. Your CPU works harder with 4 modules instead of two tho.
Lower CAS and higher speed does have an effect on performance. It's oft parroted that there is no effect in gaming but this certainly is not true. There is an effect, the question is whether it's noticeable enough to see subjectively as opposed to benchmarks and whether it's worth the cost difference.
22.3 % (SLI) increase in minimum frame rates w/ C6 instead of C8 in Far Cry 2
18% (single card) / 5% (SLI) increase in minimum frame rates w/ C6 instead of C8 in Dawn of War
15% (single card) / 5% (SLI) increase in minimum frame rates w/ C6 instead of C8 in World in Conflict
OK, thank you for your advice and the links. It seems that for an i7 and Sandy Bridge the differences generally don't exceed a 10% difference in minimum frame rate. The difference between a 2x2GB and a 4x4GB kit was minimal for Sandy Bridge. Now, assuming that's all similar for an older i5 750, I think I'll just add another kit of 2x2GB @1333Mhz/CL7. The bottleneck for me seems to be the amount of memory, so I hope that this upgrade is sufficient.
So once again I thank both of you for your advice.
(Interesting fact: higher frequency memory was easy to find, but CL6 memory doesn't seem to be available in the Netherlands. On what is probably the most comprehensive computer parts price comparison site here only 1 out of a total of 723 memory kits had a CL of 6, and that was a triple channel kit.)
EDIT: I'll look around a bit more to see how to close this question or at least to at (solved) to the thread title, but I can't find how to do that, as I'm not allowed to edit my OP. My question has been answered, however.
You will have more luck finding higher clocked higher CL9 (or 10-11) RAM than 1333/CL6. I got low voltage 2000 9-9-9-24 RAM running at a standard 1333 speed at 5-6-5-16 latencies, and I can tell you it's pretty fast. 3 years running, no problems whatsoever.
Being inversely proportional to frequency, low latency becomes an important feature when tweaking but you don't want to push up the clocks (and voltages).
It's what sets apart good from ordinary ram.