Overclockable DDR RAM for AMD opteron 165 or 3800 x2 system

can u guys please recommend me some good RAM? i want to overclock my CPU using an asus a8n premium and i would like some reccomendations on some good overclocking RAM. I would like 2 gig minimum.

(Comp used for mostly gaming but also surfing)


Also i am on a kinda budget to nothing toooooo expensive pls. Am willing to pay a bit though
i have many many questions:
what speed of RAM should i get??

DDR266,333,400,433,466 OR 550??

i dont really understand the difference between them??
Also what CAS latency should i get?
if ddr 550 is the quickest RAM then why is most RAM 400?
Are high speeds not good for overclocking

 

By default Athlon64/Opteron are designed to work with DDR400-PC3200 although the latest CPUs can use ratios which run the RAM faster than HT (200mhz which is DDR400 by default). To o/c you don't actually need RAM any faster than DDR400 as there's no performance penalty for using a RAM speed slower than HT (A64 'FSB'). Things are different for P4 & AthlonXP where it was ideal to keep the RAM equal to FSB.

For optimal performance on A64 you do want faster RAM and that's where DDR faster than 400 comes in. However these tend to have higher latency as well as a higher price tag so it is worth considering whether or not it's worth forking out the extra cash for that little extra speed boost.

Latency is time spent waiting to access the RAM so lower is better but a very fast raw speed can overcome this (which is what DDR2 strives to do). CAS Latency (CL) is the most quoted and generally most significant one. CL2.5 is average with CL2.0 being that little quicker and CL3.0 being that little bit slower. IMHO you should go for CL2.5 as the low latency tends to demand a price premium and CL3 is a thing of the 1990's IMHO.

It's a bit of a toss up between normal-ish speed with lower latency versus higher speed with higher latency. Personally I'd suggest simply getting a decent brand of DDR400-PC3200 CL2.5 and put any extra cash to the gfx card, CPU, mobo or even cooling. If you want to o/c your CPU it makes much more sense to get a good mobo as well as choosing your CPU carefully.

 

can you recommend some good RAM for overclocking without having to change the divider?

 

Well the Athlon64-X2_3800+ runs at 10x200=2.0ghz by default and I'd expect to o/c it to between 2.4ghz and 2.6ghz. They would require 240mhz and 260mhz HT if you keep the 10x multiplier (which can only be lowered anyway). That means you'd require PC3800 and PC4200 respectively. Corsair or Crucial's Ballistix would be my top choices but AFAIK Crucial don't do 2x1GB which is what you should get if you want 2GB total system RAM. You could check but you may find such fast RAM uses CL3 (likely 3-4-4) which may not make it much faster than the much cheaper stuff. It's up to you but don't fear using a divider for the RAM as it doesn't matter for Athlon64 which has the memory controller integrated (inside the CPU). As the RAM can't run at full CPU speed it's effectively always running on a divider, the HT bus is simply something for it to syncronise to.

 

ok thanks a lot.
i think i will try to find a cas2.5 2x1gb kit somewhere

is that possible??

 

There are a few cas 2.5 1gb sticks but most 1gb sticks are rated to cas3, If ou look at some of the Cosair XMS the PC4000 - PC4400 is cas3 but with abit of tweaking it could run on cas2.5 or even cas2

 

what do u mean, "a bit of tweaking"??

remember im a noob

 

In other words, you may need to increase the memory voltage so that the memory is more stable at these tighter (lower) cas latancies, there are guidelines to voltage control, these are ushaully stated in the memorys product descripition showing the maxium reccomended voltage (if you use a higher voltage than the specified maxium you may damage and viod your warrenty) but you will probably only need to increase it a tiny bit, say 2.7v is stock, then you'll probably only need 2.8-2.85v (example only, you may not even need to change the amount of voltage)

Hope that clears things up

 

ok thanks
soz bout this but another question
u know the memory timings, what does each number stand for? and which should i loosen first to enable a better CPU overclock?

 

Have a look at this post. In fact, check out this recent article

 

Don't know how I missed that one! Nice write-up

 

i was under the impression that tighter timings (latencies) are more important than speed on A64, so running a divider wouldnt kill performance much ?

edited :typo

 

AXP hated dividers, A64 doesn't really fuss about them. Latencies are reasonably important on A64, hence why a divider's a good plan.

 

Yup as said the AthlonXP was certainly optimal when the RAM speed was equal to the FSB, ie. not using a divider. However on the Athlon64 the memory controller is integrated (in the CPU) so there isn't truly a FSB any more and since RAM can't run at full CPU speed it's effectively always running on a divider. The HT Bus is simply something for the RAM to set itself by and there's absolutely no need at all for the HT and RAM to run at the same speed. Low latency will yield increased performance but you can also gain increased performance by running the RAM at a faster speed too, obviously the ideal is to have both!

 

i looked on newegg, even tho im in london, and some of the 2x1Gb sticks were CAS2. Are these the ones to go for, or are they not worth the price hike?

 

It all depends how much you're willing to pay for every last bit of performance. The diffs aren't huge by any means, I would personally strive for CL2.5 but CL2.0 may not be worth the asking price, it's up to you.

 

ok, ty , and finally, which timing should i loosen first? coz the article didnt tell me.

 

If you use the notation of 2.5-3-3-8 then I'd raise the latter 3 when needed, and then the first timing (CL) if looser timings are still desired. So 2.5-3-3-8 to 2.5-4-4-10 to 3-4-4-10. That's what I do. It's well worth benchmarking in areas most relevant to you as you may (or may not) find DDR500 3-4-4-10 preferable to DDR450 2.5-3-3-8 or DDR400 2-3-2-6 (for example).

 

I know it's a late interjection, but i've used my 3500LL Pro for weeks now, near religiously. Why? 280Mhz @ 3-3-2-0 is 105% stable @ 2.83V. This memory, though rated for DDR433, has quite a few showings of speed in the wild... If you're willing to splash out, this kit is insane.

As to loostening timings, the CAS latency will afford the largest of jumps for you.

 

Is that 1Gb tho? Loads of 2x 512 kits will run at that, or faster. If that's 2Gb then that's good. Another solution is the Corsair XMS4000PT 2Gb kit. Very inexpensive, and good for 270 to 280 at 2.8v with around 3-4-4-8 or so... with 1t timing.