Please assist me with a FINAL comprehension of HTT and FSB ~ A64 x2

[Mista.Hughes]

Fellas I have read and READ over and OVER to get a complete understanding of this . I am planning on doing a personal build for myself and don't get the HTT in it's entirety so to make it simple ..

Which would be better for smoother TRUER (in all benchmarks) performance
memory scenario > (4) Mushkin 512 mb bh-5 lvl II known to be capable of 250 fsb 1:1 w/3.2v

A.) 250 fsb w/cpu mult 12 running at 3000 mhz final ( 1:1 )
w/ a 4800+ x2 (or op 180) known to be capable of 3ghz+ (12 multi right ?)

B.) 300 fsb w/cpu mult 10 running at 3000 mhz final ( 1:1 )
w/ a 3800+ x2 E6 (or op 170) known to be capable of 3ghz+ (10 multi right ?)
~ using 6/5 divider correct ?

I would be running the Asus A8N32-SLI and the 2 gig of Mushkin bh-5 (original lvl II)

any other input besides the choice a or b as the top performer would be great also , but that's what I think for now is all i NEED to know ..

Cost aside and cache differences aside guys ... ( act like 4800 has 512+512 please )
thanx so much

[Mista.Hughes]

oh one more thing please - does the A8N32-SLI have 4/3 divider for fsb vs. memory ? if it does is there any disadvantage in anyway with doing that ?
:rocker:
thank you

[nn_step]

they will achieve about the same but there isn't a ram divider off the FSB, rather a divider off the CPU speed.
basically there is the FSB, the HTT, and the CPU speed.
the CPU speed is the FSB times the cpu multi
the Ram speed is the CPU Speed divided by the Divisor
the HTT Speed is the FSB times the HTT multi
HTT speed will not have much effect on performance or benchmarks (unless you are running Crossfire/SLi) Ideally go for highest possible CPU speed and then tweak the Ram speed up.

[Mista.Hughes]

Right so I read like 5 guides in full about the a64 architecture and how it works / how to set it up and just over the last few days went over them one more time ...
Along with reading thruout this board also ..
What I don't get is between choice A . and choice B . which would be the best performance wise and does either have drawbacks /advantages over the other ?
like i.e even though the fsb of B is greater than A - does any part of the system do WORSE when the cpu isn't running 1:1 with the mem / bus system ? or i.e # 2 would any benchmark do better with option A than B ?

thanks NN

[Mista.Hughes]

Sidenote - I wanted to keep my ram to use at it's full capabilities that's what got me going on this quest to figure out how to work around it ( work it in first )

[nn_step]

well technically the CPU NEVER runs 1:1 with the Memory but memory bandwidth and latency are not problems for AMD, since in that form it is vastly ahead of Intel. The thing about memory that you should aim for is the lowest latency, since Bandwidth isn't even remotely a problem.
The lower the Ram latency the better, but you should sacrifice it if you can gain CPU speed.
One of the nice things about AMD is that they aren't even remotely constrained by their Buses

[Mista.Hughes]

uhh what was I asking again .. like what would you do ..

[Mista.Hughes]

Ideally go for highest possible CPU speed and then tweak the Ram speed up.

so if both final clocks are the same the 300 fsb 6/5 setup isnt better than the 250 fsb 1:1 setup ?

sorry for calling what I was thinking HTT in the original post I just meant the way a64 nf4 works compared to say nf2

[nn_step]

it depends entirely on the latency of the Ram, for example the latency of Ram @ 2-2-2-5 @ DDR400 is better than the latency of ram @ DDR-500 3-3-3-8

[Mista.Hughes]

are you drunk ?

[Agent11]

:rofl: :up:

http://forum.abit-usa.com/showthread.php?t=74028

The
AMD64 Overclocking Guide by
Peanya
"Starting out, we want to lower the CPU multiplier to 8 (or 7 even) and set the memory divider to DDR333. We will not adjust any voltages for now, and we'll leave the memory timings to default or you can relax them more. Also set the AGP/PCI to fixed 66/33MHz. Now that we've done that, we can raise the LDT(FSB) bus up. While keeping the memory and CPU at or below stock speed, let's set the LDT to about 230... save your settings and boot up. Check for stability by running benchmarks such as Memtest, Prime95, 3DMark, etc... If stable, then we can raise it another 4 to 10MHz. Keep going until you start to lose stability. This will determine the max the LDT bus will go. Beyond that, you can raise the NB and HTT voltage a notch or two. Don't try going to the max on voltages or frequency right away! You need to take little steps. I've found out that beyond 255MHz, you will need to bump the HTT and/or the NB voltage a notch. Make sure to test for stability before proceeding!

Now that we have the LDT frequency figured out, we know what it can and cannot do. The next step is the memory. As with all overclocks, don't raise the memory voltage until you cannot get any further. Relaxing the timings also helps with overclocking too. You can push the memory as far as it will go, or the LDT bus will go. Start by setting the divider back to DDR400 and setting the LDT to 200, then work your way from there. Now if you have DDR500 memory, this means you can start at 250MHz, assuming you have achieved that or higher with your LDT bus. You did keep your CPU multiplier low, as to not push it beyond stock now, didn't you? We're doing this to single out where the max on the overclock is.

Another thing about memory and the LDT: it's not like the P4 where getting the max FSB gave the max performance. As long as you're over 800MHz on the LDT bus, it's not going to hold you back performance-wise. The key to the performance with the memory is the speed and timings. 2-2-2-10 timings at 200MHz will yield more performance than 3-4-4-10 at 225MHz. Finding that optimal frequency to timings is the key. Typically we want to use the DDR400 setting for the memory to maximize bandwidth, but depending on the CPU and multiplier it has, we might want to use dividers. An example would be pushing a 2800 far, where the memory will not. So we'd want to use a high LDT speed to make that CPU get far, and a divider because the memory is limited.

Finally, we get to the CPU. Since we've found out the limits of the LDT and memory, we now know what they can and cannot do. So the next step is to set the LDT back to 200MHz, and the CPU multiplier back to default. From there, we will slowly adjust up the LDT speed while also adjusting the memory timings, speed, and voltage to what we know it will do. Don't take the CPU to the max from the start! Again, go in little steps. Just because the computer will boot up does not mean it is stable. Eventually you will hit a wall here too. With the CPU overclock, always check your temperatures. "


Try reading this, then see if it makes sense.
Reading the posts of people who don't get it getting extra help and going to the other linked guides may help aswell.


so if both final clocks are the same the 300 fsb 6/5 setup isnt better than the 250 fsb 1:1 setup ?

sorry for calling what I was thinking HTT in the original post I just meant the way a64 nf4 works compared to say nf2

the CPU speed is the FSB times the cpu multi

the Ram speed is the CPU Speed divided by the Divisor

)
Ideally go for highest possible CPU speed and then tweak the Ram speed up.

That is all you need to know..I think the explanations are confusing you. Once you go about it, you will get the hang of it pretty quickly.

[Mista.Hughes]

nn_step no disrespect - just seemed you weren't really answering anything I asked at all . :toast:
I was 99% sure that memory speed and timings were a factor so yes and that's the main reason I had already said I wanted to clock the system around the memory basically .
I definately want a final 245/250+ freq on the ram at 5-2-2-2 or 11-2-2-2 or whatever is optimal . They ran that at 1t also in dual channel on the nf2 ( 251mhz fsb w/ 3.2v ) - both sets ( and then some with more volts ) so the only thing I will need to figure out is if they'll also do that in 2x dual channel with all slots filled . From what I gathered I probably will need to run 2t for that to happen on the Asus nf4 ..

I was just confused somewhat because the last system I actually tuned and tweaked to its max was an nf2 and that HAD TO BE 1:1 for system to run at peak .

Agent11 - I know HOW to do it all ( not 1st hand yet ) but I jsut didn't get which route I should be reaching for A. or B. :fact:

sooooo . 250 1:1 with the cpu and htt x4 or 300/250 6/5 divider ? with htt at x3 for a 1800 HTT final speed

[Mista.Hughes]

Oh also which of the 4 cpus I listed is going to get 333 fsb with ease " statistically " ?
opteron or x2
considering working this route also if the motherboard can do a 4/3 divider
or maybe I should also ask if the Asus mobo can do 335 easily along with the toledo cpu

[Agent11]

get the opteron 180. and the best lowest cas ram you can afford.

A high even multi is always good.

[doompc]

DDR333 setings will be to tight to 250MHz.
Start with all stock setings (DDR400), open Memset, take a screenshot.
Now set all that timings manualy in the BIOS, with DDR333 memory frequency and increase the base clock to 300MHz ;)

[afireinside]

There are no x:x ratios. There are DIVIDERS which are CPU SPEED / DIVIDER = RAM SPEED.

HTT clock doesn't really matter as far as performance goes.

[ozzimark]

it depends entirely on the latency of the Ram, for example the latency of Ram @ 2-2-2-5 @ DDR400 is better than the latency of ram @ DDR-500 3-3-3-8
been a while since i've messed around with ddr1, but i recall those two being roughly equal.. :D


and to expand on what AFI said, there are ratios, but they don't directly set the ram speed.

ram speed is indeed cpu/x where x = ceiling( cpu multi / memory ratio )

200mhz = 1/1
166mhz = 5/6
133mhz = 2/3
100mhz = 1/2

plus a few others, like 183mhz which is 11/12 :p:

[nn_step]

been a while since i've messed around with ddr1, but i recall those two being roughly equal.. :D


and to expand on what AFI said, there are ratios, but they don't directly set the ram speed.

ram speed is indeed cpu/x where x = ceiling( cpu multi / memory ratio )

200mhz = 1/1
166mhz = 5/6
133mhz = 2/3
100mhz = 1/2

plus a few others, like 183mhz which is 11/12 :p:
close but it is more like DDR-400 @ 2-2-2-5 has similar latency to DDR-600 @ 3-3-3-8 ;)

[doompc]

At DDR600 3-3-3-8 you have the same latency but a lot more bandwidth.
But BH5 can't work with CL3. And to get them to 300MHz you'll need a lot more than 3.2v...

[nn_step]

At DDR600 3-3-3-8 you have the same latency but a lot more bandwidth.
But BH5 can't work with CL3. And to get them to 300MHz you'll need a lot more than 3.2v...
but at the same time you don't need that extra bandwidth with K8 Processors. Heck they are swimming in more bandwidth they need, even at DDR-266 (provided you actually run Dual channel) for a Dual core processor.

[ozzimark]

close but it is more like DDR-400 @ 2-2-2-5 has similar latency to DDR-600 @ 3-3-3-8 ;)
THAT i did testing on. off the top of my head, the former was around 45ns latency, the latter was 38ns. same cpu speed. ;)

i wish i still had my ddr1 rig around to do testing on..

[nn_step]

THAT i did testing on. off the top of my head, the former was around 45ns latency, the latter was 38ns. same cpu speed. ;)

i wish i still had my ddr1 rig around to do testing on..
if you want I can lend you a pair of my BH ;)

[markr]

Is it possible to get 4 sticks up to 250Mhz at 1T on that board?