Lower timings are better, but the don't make any difference in games/apps.They are mainly important for OverClocking.Also 2000 vs 1600 doesn't make a noticeable difference either.I would go with DDR3 1600 because its cheaper(I assume ?),has lower timings and also even if you want to OC a lot,DDR3 1600MHz is quite good.
I am sorry to disappoint both gentlemen above, but the correct answer is that it depends on the application. When there is a lot of data to be transferred then memory speed (bandwidth) is more important.
I can't suggest a specific memory module as there are so many around. Perhaps Maziar is more informed than me and could suggest something nice.
Memory helps in terms of not being a bottleneck both on the CPU and on the bus when overclocking. So it will not hinder the actual CPU headroom, but if you reach its limits it will prevent the system from going any further. Bottom line if you are going to overclock your system, you should be getting some reliable sticks (you find that by Googling around and reading how other people found that brand and how it performs in general).
so the difference isn't much between DDR3 1600 8-8-8-24 and DDR3 2000 8-8-8-24. So it is not worth the extra dollar.
What memory would you recommend for a gaming machine?
Does memory help in terms of overclocking the CPU?
Yes the difference isn't much like i said, but you didn't mention the price difference.
As for recommendations, well the one that you have find(DDR3 1600 CL8) seems a good choice.
And as for OC'ng,yes it helps because you have to tweak the RAM's voltage,speed and timings in order to OC your CPU
what everyone else above stated is very true, BUT, it ALL depends on your system.
What socket are u using ? LGA 1366, LGA 1156, or are u going for AMD, everything must be taken into consideration.
For example, if u are using an LGA 1366 with an i7-920 CPU and u want to OC it, u will need RAM at least 1600 Mhz since they must scale together. Latencies, the lower (8-8-8-24) they are the better. Using this configuration (LGA 1366 with i7-920), if u do not OC in any way (not even XMP, Extreme Memory Profile, which is a OCing preset profile in BIOS), it wont mater what kind of RAM u are using because it will hover at 1066 Mhz!
So please, give us the configuration of your comp, or what configuration u will want to build so we can better answer your question.
CPU Cooler and motherboard are important, but RAM is important too because like i said you have to tweak the timings/speeds/voltages in order to get a good OC on CPU.
For black editions CPU,which have unlocked multiplier,its far easier to OC than CPUs with locked multiplier but still you may need to change some other settings rather than only the multiplier.
Maziar is right, u dont need at least 1600Mhz for a "decent OC"
going for ~3.8 Ghz, however, will require some 1600Mhz sticks for a good match since they will be set to 1532Mhz (valid for the LGA 1366 with an i7-920 example).
For your configuration, its best to look around (forums, etc.) what others have tried and then try it yourself. OCing is more of a "personalized thing" for each configuration, but u can start small, with a "small OC" and then work your way up (if u are not satisfied), while monitoring temps, stability, etc. until u feel u reached either its maximum potential or your satisfied with the results. Try searching for some clips about how others have done the OC (on configurations like your own) together with posts and articles; thats how u start your OCing career