The lowdown for overclocking...

[DVad3r]

I'm a noob that managed to overclock my system, but I still have no clue how it all works. If my memory speed is set to DDR 333 and cpu z shows it running at 208 mhz then that's more like DDR 416? What is 1T and 2T? And mostly what is the HTT setting 1-5? My current config is 10x250x1T @ 4 HTT and DDR 333 = 2500 mhz with the mem running at 208 mhz? Does that sound correct? Also my ram is rated at 250 mhz, so if I go to DDR 400 my memory runs at 250 mhz which to me means DDR 500, how does this affect system stability if the memory is rated for 250 mhz? Anyone can give this a nice breakdown and maybe add it to the overclocking guide sticky?

Thanks.

 

[otispunkmeyer]

if u set your memory to 333 (then its been set in a 5:6 divider) for every 6 mhz on your cpu's fsb, you will have 5mhz on your ram. so i see you said you have 208mhz memory, so from that i deduce that you are running a 250mhz FSB, which indeed you are.

HTT is HyperTransport, its what the CPU uses to communicate with northbridge and a few other things, for your mother board it should be set at x5 at stock. but stock FSB is 200. 200x5 = 1000 which is correct. however you have a 250Mhz FSB so i would suggest running the HTT at x4 250x4= 1000. so your correct there too

1T and 2T is the command rate, basically how i understand it is like this. at 2T the system provides the ram with a command that lasts 2 cycles. this gives the ram enough time to change its logic level and acknowledge the command. at 1T the command is simply presented to the ram for 1 cycle. so for 1 cycle you need ram that has very low capacitence in it workings, as its the capacitence which limits the speed at which a 1 can turn to a 0.

for A64 1T is much better than 2T

if your memory is rated for 250mhz, then in your current set up you can run the memory and the FSB at the same speed, ie 250mhz each. just try it. running a 1:1 ratio is much better than running out of synch with a 5:6 ratio. but at 250mhz your ram may not be able to sustain that 1T timing an u may have to drop it back to 2T

 

[DVad3r]

Thanks for the reply otispunkmeyer, I was curious how the memory dividers worked.

 

[otispunkmeyer]

400 = 1:1 ratio
333 = 5:6 ratio
266 = 2:3 ratio

this is RAM:FSB

to run ram at 200mhz

1:1 = 200/200
5:6 = 200/240
2:3 = 200/300

 

[DVad3r]

So your saying that my DDR333 is not good at 208 mhz and that I should go to 2T instead of 1T? But I heard from other members on these forums that 2T just is not good, and I will get a big performance hit.

 

[zakee00]

No, don't use 2T if you can avoid it AT ALL. It is always better to run at 1T, even if you have to lower the devider in order to stabilize it. Also, A64's enjoy tighter timings about as much as a higher devider (aka ram@250MHz 2.5-4-4-7 is about equal speedwise to ram at 200Mz 2-2-2-5). Just something to keep in mind.

 

[Icopoli]

Um, I'm not exactly a computer newb or anything here, I do tech support for a living, I don't know too much about OC'ing AMD systems, but I've clocked my A64 3000+ from 2.0ghz to 2.4ghz without touching the multiplier, changing the HTT to 240mhz from 200mhz. Runs stable with 3DMark 20055 doing 12 loops (I score about 3500 I think, that box is at a friends right now) ram timings at like 2.5-2-2-5. From what I've read here, there's noway in hell that my box should even POST.

My rig is an ASUS K8N-E Deluxe, A64 3000+ (754), 512mb Kingston Ram, HiS x800 Pro @ XT PE speeds w/o the pipelines opened.