couple A64 oc Qs

C

chipmonk010

Weaksauce
Joined
Oct 31, 2004
Messages
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ok so i just got a msi k8n neo plat 939 nf3 ultra board n a 3000+ 90nm proc.
first of whats the max safe temp w/ a64? i know with xp 50-55 was like the max you should go.
it seams like i idle at like 37 and then with prime 95 going it goes up to 52 thats a hell of a jump is that normal?
HT mult? 1X-5x i think this is like the multiplyer for the 1000mhz bus or whatever but when ocing should i first lower this to 4 so i dont go over 1000 i heard that if you go over 1000 things meltdown blowup bad things is that true?

any other A64 tips?

Thanks for any help guys
 
heh, sounds like you're having fun with your new system ;)

for the temp, the highest i would personally go is 60ºC under full load. anymore is just getting too hot.
large temperature jumps are pretty normal, but if you suspect it to be too large, consider reapplying your heatsink . if it wasn't quite perfect the first time, it will bring idle temps up a bit, and load a bunch more.
as for the ht link speeds, you should try to keep it under 1ghz. you can try to find the top end of it if you'd like, cause nothing bad will happen to your board by setting it too high, you just might have to reset the bios, but that's trivial.
 
yeah i sure am having fun! this thing is sweet, the biggest thing i noticed is that my corsair valueram is running at 5200MB/s! theres pleantly of tweaking to do and this board has everything you could ever want
Thanks for the help n quick reply once im fully up ill post benchmarks!
 
what do you have the ram timings set to? you should be getting around 6000mb/s. check to make sure the command rate is at 1T, that makes the biggest difference.
 
yeah i changed that and got 5700 MB/s but what about these other timings: bank cycle time (11),
and DRAM idle timer (16)

what are the optimal setting for these, should i even change them?

thanks again for the help guys
 
i'd set them to auto and enable agressive timings in the main cell page.
try downloading a64 tweaker, taking a screenshot of it, and posting it up here along with the ram speed and bandwidth you get at those settings.
 
screencap.gif

This is what i have setup right now, rock solid and stable!

if i enable agressive timings i get another 50MB/s in sandra but prime95 fails after 3 mins, that tweak program looks cool theres alot of settings i didnt know about
 
ah.. hmm, your memory is running at 220mhz
low latency is far more important for a64's than memory bandwidth is, especially on a dual channel system
try to do 9x245 with the ram set to "166mhz".
you might have to bump the voltage up some cause you're doing 2.2ghz, but it'll lower the ram down, so you can try to get as close to 2-2-2-5 timings as you can get
(btw, what kind of ram do you have?)
 
so the mem divider is more like a lock then a divider on A64, so even if its below 200 its still gonna be faster? and ill be able to push the MB to max htt without worrying about my crappy ram (corsair value ram 2x 256 pc 3200) . ill be upgrading ram in a couple weeks.
ill try what you said n see how high i can get thanks!
 
no, the mem divider is still a divider. here's how it works.
there's the htt.
from this, there is an ht link multi. this sets the final hypertransport speed (try to keep this number under 1ghz)
then the cpu multi. finding cpu speed is straighforward. htt * cpu multi = cpu speed.
after this, there's the memory divider. since the memory controller is on the cpu, this divider reduces the cpu speed to the ram speed. this is where things get complicated. bear with me for a bit here

the settings the k8n neo (and most other boards) has in the bios are dividers. breakdown is as follows
200mhz = 1:1
166mhz = 5:6
133mhz = 2:3
100mhz = 1:2

now those ratios are the speed the bios tries to keep the ram at in relation to the htt, but since the ram is set from the cpu, it has to do a bit of divider fiddling.
the ram divider = cpu multi / ram ratio rounded up to the nearest whole number.

so if i wanted 2.4ghz with my ram at 200mhz, i would do this:
240mhz, 10x multi, 166mhz
then the cpu speed would be 2400mhz.
10 / (5/6) = 12
2400/12 = 200mhz
presto, my ram is 200mhz.

but say i can't do 2.4ghz, and i wanted something a bit slower while still keeping my ram at 200mhz
then i think for a bit and try this
245mhz
9x multi
166mhz.
first you say wait, the ram will be overclocked (by ratio, it should be 204mhz) but this is what's annoying about a64's.. it's not
9 / (5/6) = 10.8, so it rounds up to 11, thus reducing the ram speed from what it would have been if it was a ratio from the htt.
so now 245*9 = 2205mhz
2205mhz / 11 = 200.5mhz

hehe, yeah, that was a lot of info, but i think it'll help you out a lot if you can fully understand how it works ;)

now get back to my oc'ing guide :D
 
i got ya, once i used the divider it made it totally clear thanks for the breakdown. its weird how they set that up. the board is screaming! i dropped the mem divider to 166 and now my htt is at 260!!! 3000+ cpu at 2.3!!! im running prime 95 as i type and no problems yet i already ran all the sandra stuff and my final htt is 1040 and running fine tho if i try goin further ill probly drop to the 3x ht multi.
Thanks a million man all i needed was to drop that mem divider
 
so if i wanted 2.4ghz with my ram at 200mhz, i would do this:
240mhz, 10x multi, 166mhz <---- Where does this 166MHz value come from?
then the cpu speed would be 2400mhz.
10 / (5/6) = 12 <--- What exactly is 12?
2400/12 = 200mhz
presto, my ram is 200mhz.

Can you translate that into more of a "ram overclocking for dummies" way or is that about as simple as it gets? I was just very lost by your example.

Doesn using anything besides 1:1 slow down your computer? You didn't mention anything about that in this post.
 
unimatrixzer0 said:
so if i wanted 2.4ghz with my ram at 200mhz, i would do this:
240mhz, 10x multi, 166mhz <---- Where does this 166MHz value come from?
then the cpu speed would be 2400mhz.
10 / (5/6) = 12 <--- What exactly is 12?
2400/12 = 200mhz
presto, my ram is 200mhz.

Can you translate that into more of a "ram overclocking for dummies" way or is that about as simple as it gets? I was just very lost by your example.

Doesn using anything besides 1:1 slow down your computer? You didn't mention anything about that in this post.
Click to expand...

i have the same exact questions.

The first Q - "where does the 166mhz comr from" i think that's the ram ratio. 166 = 5:6

The second Q - "what exactly is 12" i think has to do with when eclipse said "the ram divider = cpu multi / ram ratio rounded up to the nearest whole number." so the CPU multi (10) / the ram ratio (5/6) = ram divider (12)


is that right?
 
Yep. For example, on my old RevE 3000+ and PC3200 memory, I ran it at 150MHz mem divider (3:4). So....

9 / (3/4) = 12

Then I set my "fsb" to 267 MHz.

267 * 9 = 2403 MHz

Then I can calculate what my memory will be running at by doing the following:

2403 / 12 = 200 MHz

Quick summary:
CPU Multiplier = 9
Memory Divider = 150 MHz or 3:4
"FSB" setting = 267 MHz
Final CPU clock = 2403 MHz
Final Mem clock = 200 MHz
 

I'm just having trouble knowing which ratio to use.

if i have my HTT mult set to 3x then i should be at 2:3 right? (mem = 200*2 and HTT = 200*3) ?

with that math, i get the following

250HT * 9 = 2250mhz clock
9 / (2/3) = 13.5
2250/13.5 = 167


where am i off? it must be the ram ratio.

zv
 
Ram ratio is going to be a different setting all it's own. Your BIOS should have independent settings for:

1. HTT/"FSB" Speed
2. Mem Speed/Divider
3. HTT Multi
4. CPU Multi


So from my example, the settings would be:

1. 267 MHz
2. 150 MHz/3:4
3. 3X (set this as so the final speed won't be over 1000 MHz) (267 * 3 = 801 MHz = safe)
4. 9X


From your example:

1. 250 MHz
2. 133 MHz/2:3
3. 4X (250 * 4 = 1000 MHz = safe)
4. 9X

Calculations would be as follows:

1. Final CPU speed
...250 * 9 = 2250 MHz

2. Memory Speed Calculation Divider
...9 / (2:3) = 13.5 (rounded up to 14)

3. Final Mem Speed
...2250 / 14 = 161 MHz

If you are using PC3200 memory, your best settings with a 250 MHz HTT/FSB would be as follows:

1. 250 MHz
2. 166 MHz
3. 4X
4. 9X

FINAL CPU SPEED:
250 * 9 = 2250 MHz

MEM CALC DIVIDER:
9 / (0.83) = 10.8 rounded up to 11

FINAL MEM SPEED:
2250 / 11 = 205 MHz
 
DejaWiz said:
Ram ratio is going to be a different setting all it's own. Your BIOS should have independent settings for:

1. HTT/"FSB" Speed
2. Mem Speed/Divider
3. HTT Multi
4. CPU Multi


So from my example, the settings would be:

1. 267 MHz
2. 150 MHz/3:4
3. 3X (set this as so the final speed won't be over 1000 MHz) (267 * 3 = 801 MHz = safe)
4. 9X


From your example:

1. 250 MHz
2. 133 MHz/2:3
3. 4X (250 * 4 = 1000 MHz = safe)
4. 9X

Calculations would be as follows:

1. Final CPU speed
...250 * 9 = 2250 MHz

2. Memory Speed Calculation Divider
...9 / (2:3) = 13.5 (rounded up to 14)

3. Final Mem Speed
...2250 / 14 = 161 MHz

If you are using PC3200 memory, your best settings with a 250 MHz HTT/FSB would be as follows:

1. 250 MHz
2. 166 MHz
3. 4X
4. 9X

FINAL CPU SPEED:
250 * 9 = 2250 MHz

MEM CALC DIVIDER:
9 / (0.83) = 10.8 rounded up to 11

FINAL MEM SPEED:
2250 / 11 = 205 MHz
Click to expand...



well laid out. you made it very easy to understand.

thank you!

zv
 
my mobo is only 800mhz HTT, so i don't think i should do the 250 with a 4x HT multiplier. I'll probably do 267 with a 3x multiplier. (which is 801, is that a problem?)




I'm still confused how you decide which mem speed/divider you chose (133, 166 etc)

is it only limited by the max of your memory? so if i have DDR 400 mem, i can't end up with more than that at the end of the math?

for example, with your example from above, if i used a 1:1 ratio, the memory would be at 267 (*2 for DDR) which would be more than it's capable of?

is that why dividers are needed?

zv
 
zero_vertical said:
1. my mobo is only 800mhz HTT, so i don't think i should do the 250 with a 4x HT multiplier. I'll probably do 267 with a 3x multiplier. (which is 801, is that a problem?)


2. I'm still confused how you decide which mem speed/divider you chose (133, 166 etc)

3. is it only limited by the max of your memory? so if i have DDR 400 mem, i can't end up with more than that at the end of the math?

4. for example, with your example from above, if i used a 1:1 ratio, the memory would be at 267 (*2 for DDR) which would be more than it's capable of?

5. is that why dividers are needed?

zv
Click to expand...

1. Shouldn't be a problem, but if you experience any quirkiness with your system, back the multiplier down even further.

2. It's all trial and error. The equations are helpful in deterning what ideal setting could be before you physically set them.

3. You can end up with more if you know for a fact your memory is capable of being overclocked.

4. Yes, it would be more than it's capable of, unless number 3 above is true.

5. Absolutely. ;)



zero_vertical said:
well laid out. you made it very easy to understand.

thank you!

zv
Click to expand...

Glad to help!
 
DejaWiz said:
1. Shouldn't be a problem, but if you experience any quirkiness with your system, back the multiplier down even further.

2. It's all trial and error. The equations are helpful in deterning what ideal setting could be before you physically set them.

3. You can end up with more if you know for a fact your memory is capable of being overclocked.

4. Yes, it would be more than it's capable of, unless number 3 above is true.

5. Absolutely. ;)
Click to expand...

youdaman. now to get out of this damned office and home to my new (old) toy. thank god for boneyard parts. i could care less if this thing explodes into flames. it's like the expirimental rig. i don't understand how people learn to OC on brand new, high end hardware though. kind of seems irresponsible.

zv
 
okay. learned a lot today. :D


i'm an hour into prime 95, and i'm pretty sure i booted into windows twice as fast as ever before.

Here's the Story


HT Bus: 245mhz
HT Mult: 3x
CPU Mult: 9x
Divider 166mhz
VCore 1.52v

Clock: 2207mhz
Temps 39C (steady)
Stock HSF


I only have the HT Link at 736, because this board has 800mhzHT ( :( ) fortunately, the bios is amazing.

anyways, where's my capital best spent at this point? what nets me the most bang for the buck assuming i stay stable? should i push the HT out or do i need to up the HT bus and see how far the memory goes till it breaks? she wouldn't boot windows south of that voltage, but given the temps, i'd say i've got a ways to go there. :D

I need to run a memtest86 still, because this memory is suspect. o_O

zv
 
No problem at all bud.

I just rebooted my system with my new oc settings:

HTT Multi: 3X
HTT Speed: 274 MHz
CPU Multi: 10X
Mem Divider: 180 MHz (0.9)
Vcore: 1.35V

Results:
CPU Speed - 2.74 GHz
Mem Speed - 250 MHz

:D :cool: :D :cool:
 
(cf)Eclipse said:
low latency is far more important for a64's than memory bandwidth is...
Click to expand...
Hmm...so 3-3-3-8 @ 2T running at 250MHz isn't the best idea?

I've got one of those 1GB sticks of Crucial Value RAM that you made a thread about a while ago, any idea what sort of timings I should be able to eek out of them (I have up to 3.2v to work with).

I'm a noob when it comes to RAM timings (thats why I left them at stock and cranked the clock speed), so if you could add labels to your timing suggestions I would greatly appreciate it :D
 
i've booted under 266 instead of 245, and upped the voltage a bit to get me there, and i'm into windows fine at 2.4ghz but prime craps out almost immediately (1.6v)

the memory was up a little high (215mhz), so i changed the divider down and upped the HT Bus enough toget back to 2.4. still prime craps out.

i've tried a couple different configurations down to 2.3, and can't keep prime going.

what am i doing to push prime over the edge?

I'm back to

HT Bus: 245mhz
HT Mult: 3x
CPU Mult: 9x
Divider 166mhz
VCore 1.52v

Clock: 2207mhz
Temps 39C (steady)
Stock HSF
 
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