2GB memory to buy for OC. Help!

00fil00

00fil00

00fil00

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I dont understand memory at ALL! ive been trying for 2 months now. basically i need someone else to tell me what to buy. i already bought corsair 3200 but found out i cant overclock with them. This is what i want. I would like to overclock my opteron 146 to 2.8 - 3.0ghz. How would i best go about doing that with 2gb of ram and keeping gaming performance at its best. keep in mind i have no prior experience to overclocking cpu so am a little put off with the g.skill hz opinions that say it took them ages to set up as they wouldnt work at default timings. i wont know what to do if they dont start up. But i am very tempted by them (why do some say the g.skill zx is the kit to get? is that just for low overclocks? its only pc3200! i dont understand). can some nice people please name some memory 2gb kits and tell me why they think they are the best choice for my criteria? thank you all!!!!! this is the final piece to my building puzzle and cant start till its done

P.S. almost forgot:
opteron 146 0545
asus a8n32
antec 550w
 
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The ZX is recommended (by myself too) because on an A64, tight timings are probably more important than high frequency. The reason? Because the A64 memory controller is on-die, as in on the CPU itself. The memory controller accesses and addresses the memory, I believe, and this is where the tight timings are good. Timings are how many clocks pass before the RAM performs certain actions (once again, this is my understanding, someone please correct me if I'm wrong). Thus, with the controller being on die, the memory is accessed directly from the CPU as and when needed. Thus, bandwidth (frequency) is not necessarily any better than tight timings as the high bandwidth stuff requires slack timings. So more info per unit time but accessed slower, or less info per unit time but accessed faster. You see the situation. I believe that the tightest timings actually have a small increase in performance. However, if you get high frequency RAM with tighter timings than the current standard of 3-4-4-8 1T, then this is better than tight timings. It's up to you how you go anyway, as running the tight timing RAM requires a divider i.e. RAM and FSB do not run in sync, whereas running 1:1 means RAM=FSB. Thus PC3200 RAM can be run close to 200mhz whilst still overclocking with no performance hit (on A64's anyway).

Intels are different as their memory controller is on the northbridge chipset. This means the info travels from the memory, to the chipset to the CPU. This increased path means it is better to have high bandwidth as there is a latent period in this transfer of data.

I hope that helps - it's my understanding (simplified).

Someone please correct any mistakes/errors as I don't fully understand all this myself but this is how I am lead to believe this all works.
 
but what i think though im not sure is correct, is it not that if i get pc3200 then i can only get to about 250fsb and 146 multiplier is x10 so that is a maximum clock of only 2500ghz? im sure there are ways around it but i dont know yet, i presume its this divider thing that i hear but i dont know if that would affect performance. if that is the case then why not just buy £100 cheap ram and run them on a divider if any ram can hit 3ghz with dividers?

Also i have the corsair 2gb pc3200 xms 2-3-3-6. is that bad for overclocking an opteron to 2.8-3.0ghz? is it worth the rma?
 
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Ok, let me try to explain.

Your processor speed is calculated as follows: Muliplier X HTT (commonly known as FSB). So in your case your multiplier is 10 so you will need a HTT of 300 to get to 3ghz.

Now, though your ram speed is related to your HTT speed, it does not need necessarily to equal your HTT. You can run your ram out of sync with the HTT using something called a divider. For example if you ran a divider of 4:5, then if your ram speed was 200 then your HTT speed would be 250. This practice of running a divider used to be very unpopular as it gave such a performance hit to your overall overclock, that it was often better to simply run your CPU slower without a divider than faster with one. This is not the case with the AMD64s.

So number 1, your ram is fine (in fact it is good ram), so don't worry, you can still get (if your chip is up to it) to 3ghz using a divider.

The second thing that you need to know about is timings. You may hear people talking about 3-3-3-8 or 2-3-2-6 or something similar. These set of numbers are the 'timings' and the lower they are the quicker your ram will access and process information. On an A64 platform these timings have a considerable effect on overall speed.

In answer to your last question, you can use cheap ram and run a divider and reach 3ghz. However if you get better ram that runs with lower timings it will increase your performance at 3ghz by as much as about 10%.

Finally though, let me clarify that this does not mean that ram speed is now insignificant. It is merely less significant that it used to be. In your case you could reach 3ghz with your ram at 200 at 2-3-3-6 using a 2:3 divider so that your HTT will be 300. However this will not be as quick as if you ran your ram at 250 with 2-3-3-6 timings and used a 5:6 divider instead. Now your ram won't do 2-3-3-6 at 250, but even if it only ran at 2.5-3-3-7 at 250 (still using the 5:6 divider) you might find that this is slightly quicker to your overall performance than if you ran it at 200 at lower timings and used a 2:3 divider.

All ram has a sweet spot ratio of speed vs timings. If you can find it and use it in your final overclock you'll get the absolute best performane your hardware can offer.

Hope that helps.
 
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00fil00 said:
but what i think though im not sure is correct, is it not that if i get pc3200 then i can only get to about 250fsb and 146 multiplier is x10 so that is a maximum clock of only 2500ghz? im sure there are ways around it but i dont know yet, i presume its this divider thing that i hear but i dont know if that would affect performance. if that is the case then why not just buy £100 cheap ram and run them on a divider if any ram can hit 3ghz with dividers?

Also i have the corsair 2gb pc3200 xms 2-3-3-6. is that bad for overclocking an opteron to 2.8-3.0ghz? is it worth the rma?
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Other factors come into play - memory controller - can it take the divider you want to run. The 166 divider pretty much always works, as does the 133 but others are a bit flakey. And yes, you need to find out about dividers. Cheap RAM doesn't have the tight timings. As I said, tight timings/low freq = loose timings/high freq but cheap RAM is loose timings/low freq. Tight timing RAM costs about the same as loose timing High freq RAM.

That is a decent choice. If you are worried, just get PC4000 stuff and concentrate on the CPU. A64's respond more to CPU speed than anything else.
 
smids is also quite right with his final sentane. CPU speed is the biggest factor is overall speed. That is not to say that 3ghz using ram running at 200 with 3-4-4-8 timings will be quicker than 2.95ghz with the ram at 250 with 3-3-3-8 timings or maybe even 2.9ghz with ram at 250 with 2.5-3-2-6 timings, but it does mean that overall CPU speed is the most weighty factor.
 
thank you that helped a lot, but i dont see why my ram cant do 250? is it because it is pc3200? and i heard that corsairs dont like running on dividers. im just getting worried as my time to rma it is running out and i cant turn on my new rig till march when i get one of the new graphics cards, by then it will be too late to rma anything, i only have an agp 6600gt right now in this old rig. this is why i am trying to do it all blind right now with no physical experience infront of me and its hard. so 2 questions - which would be faster, if they both overclocked to 2.8ghz, the corsair xms3200 or the g.skill hz? and secondly, would it be worth returning the corsair and going through the effort and time and worry, for this g.skill ram? considering its cheaper, probably better at overclocking or so i hear, but possibly finicky and has heat issues?
 
Ok, 3 answers there. 1) You probably can get that corsair up to 250 (assuming that it is the CAS2 stuff rather than the CAS3) but it's sweet spot is probably lower than that. I'd be surprised if you could get it to 250 at anything better than 3-3-3-8 and even that might be a push. 2) The G Skill would probably be faster (not certainly, but on paper it should win) 3) As for whether it is worth it....that's a subjective thing that only you'll know the answer to. Personally i'd probably stick with the Corsair now that I had it. This is of course assuming you have the CAS2 PC3200 rather than the CAS3. If you have the CAS3 then the odds might shift more in favour of doing a swap.
 
ive got my xms 3200 C2PT rev1.2 at 225.Thats it for 2.5 3 3 11

Im trying to look at ocz 3500 but the page wont load.Try to research higher clocks than 225 on ram imo.So some good 3500 would do

EDIT oh you already have your ram
 
ok so if i bite the bullet and narrow it down to either the g.skill hz or zx. is this my choices?

a) hz = will be able to clock opteron 146 to its full potential 2.8-3.0 with slower timings with 250>fsb
b) zx = will not clock opteron as far but will leave better low timings (is this correct? if so who cares? its only 2fps and 2 seconds of game loading faster! am i right in thinking this? surely this cant be right, as the higher clocked opteron from the hz would MORE than make up for the slight delay in loading and totally surpass it with processing power
c) zx = somehow use a divider and keep the low timings 2.5-2-3-6 AND manage to clock the opteron fully. is this correct with what dividers do? do they affect timings? i heard a lot of reviews say that the zx dont always clock as well as people say, usually only 230

is this all correct? with a multiplier of x10 which would be best for gaming, NOT benchmarking?
 
Gaming = timings. You will be running a 10x multi = 280-300fsb. Running at 280Mhz you'd need a 133 divider on the ZX unless you could get 233mhz out of it for a 166mhz divider. Running 300mhz fsb needs 133 to run @ 200mhz.

The thing about the HZ is it will clock 1:1 easier (a really good set can hit about 280). Beyond that you'd need a divider. TBH, for you, as you are a newb clocker, go for the HZ as it will be easier to work with I feel. Running all this divider stuff might be a bit burdensome + you don't have all the dividers available like the DFI does, so you'd be stuck with either 133 or 166mhz dividers.
 
Either one will get you to your maximum overclock using a divider. Just as the Corsair will.

I think that the zx will probably be slightly the fastest, then the HZ, then the Corsair. The HZ will be the least complicated to overclock as you can possibly reach your maxium overclock without using a divider.
 
ballistix die. if not after 10 seconds then in 3 months. maybe i should put this another way to make it easier, tell me if i put on the 1st divider (not sure if that is 133 or 166) then what is the required mhz i need for that? for instance 1:1 to get the cpu to 2800 id need 280mhz x 10 multiplier. if i used the first divider, the one that doesnt lose as much performance, then what values that the ram can do am i looking for? 230mhz? 250mhz? is the first divider 20%? so if i wanted to get 2800mhz out of the cpu id need ram that can do 280mhz-20% thats a ram that can at least do 224? am i right? so all i need to do is go around looking for any ram that can do 224 with the lowest timings? please god let me be right cuz i give up after this lol. its too hard. thanks for the help guys! thank you so much! your patience is welcoming.
 
yep, you're about right. You should need ram that can do 224 at as a set of tight timings as possible.

That said, this is one area that I just can't be 100% sure on. I myself am running a 166 divider and am using a HTT of 289 (9 x 289 = 2.601ghz). In theory that should leave my ram running at 240-241, instead though it runs at 236-237. I still haven't worked out why, but both everest and cpuz tell me the same thing.
 
its because the divider isnt 5/6s exactly its slightly less, it did the same thing on my board and I asked the same question last week...

Heres a useful program...

Memfreq
 
Urika! thank god. so is 166 the best divider to go for and if failing that, 133? why does everyone not do that then? because i hear a lot more about the g.skill hz pc4000 than the zx pc3200.
 
There two reasons. 1) There is still a wide belief that running a divider seriously impact performance 2) There is still a wide belief that FSB is more important than timings.

The first one is catagorically not true and the second is only part true. FSB will help, but so will tight timings. The key is to find the best balance. I think that at the moment with what is currently available in terms of ram, the best balance is something like 230-250 at 2-3-2-5 to 2.5-3-3-6, rather than 270-290 at 3-4-3-7 to 3-4-4-10.
 
that memfreq from street above solved the riddle as i had something to tinker with and see how the numbers played on each other. thanks street! and thanks uncle for hangin in there ;). all i need to do now is find a ram that will certainly hit 233 - 241mhz in pc3200 and if it doesnt go you just up the voltage a bit or raise the timings? something like that? im getting it now. any ram youd recommend that can do that? ill probably go with the g.skill zx pc3200 but its kinda hit and miss. if there was ram that would DEFINATLY push at least 240 for a little more money id go for that for safety.
 
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