Overclocking breaks things which you alone are resposible for, not AMD, not intel, not Nivida, not Ati, not xyz mobo maker. Proceed at your own risk.
this is a quick and dirty guide. I am aiming for simplicity since it's not all that complicated to OC A64's even for first timers. I am also aiming for safty so you don't kill anything so lower volts are advocated. Just good clean fun to get an FX or better from your budget chip.
VERY IMPORTANT to keep in mind at all times is hypertransport needs to be around 1000, meaning LDT x HTT (aka FSB) ~1000 or less.
Now we will
Isolate then Consolidate.
What that means is you need to test three parts of the CPU subsystem (chipset, chip, and memory) to find max speeds of each.. Then combine them for some sort of optimal overclock.
ISOLATE
Don't forget to take notes.
1. Max HTT/FSB should be first ..*only works if motherboard has locks. Most A64 boards do today. Sata 1 and 2 are not locked on some nforce mobos use 3 and 4.
-set CPU multi to 6 or 7, this will take CPU out of equation
-set memory to SPD and 100, this will take memory out of equation
-Increase HTT/FSB up until you fail to boot or there abouts, back down 5%, (HTT * 0.95), this is your max safe HTT.
2. Max Chip capable
- Set multiplier to it's maxium
-Set vcore to 1.6 -1.65 for 130nm chips, 1.50-1.55 for 90nm chips
-Set mem to SPD and 100, this will take memory out of equation
-starting with HTT 200 raise in about 5Mhz increments up to boards max found earlier or until you start failing PRIME95 which will probably happen first..only give it 5 minutes max, that's good enough for now.
-At the point it starts failing within that 5 min time period, back down 5%, (CPU MHZ * 0.95), thats your max CPU speed, now test prime again at 95% for 12 hour for stable.
Prime 95 Link
http://www.mersenne.org/freesoft.htm
3. Memory MAX
It depends what you want and type of mem you chose, LL or Bandwidth but must keep 1T (command rate) because A64 suffers big time with 2T.
-For high bandwidth set mem setting to 200 and 2.5-4-3-7 1 T and give it boards max volts, or for LL set mem setting to 200 and 2-2-2-7 1 T and give it boards max volts. (up to 2.9Vdimm is safe with all ram) ( Caution DFI/ABIT users -- do not exceed 3.0V unless you know what you are doing!!!)
-Set CPUs multi to 6-7, again to take it out of equation.
-Raise HTT up to boards max or until you start failing memtest86 test 5 and 6
http://www.memtest86.com/
-When you start failing memtest86 test 5 and 6, back down 5%, (HTT * 0.95), thats your max MEM speed.
CONSOLIDATE
The most important thing to keep in mind is CPU Speed is king. So now that you know your CPU speed from above, use it. Say it's Winchester 3000 and it's 2650Mhz prime stable and with it's 9 multiplier it needs 295 HTT to get there (9x295=2650)...NP right, but you got some value ram which only clocked to 210Mhz from your above testing. Well obviously you can't run the ram at 1:1 which would be 295Mhz, you must use a mem divider. You can use the memory divider (mem setting) to get as close as possible to your mem max found above.
This is the rough way to calculate IE close enough..
Memsetting setting
200 = HTT Mhz
183 = HTT x .90 = Mhz
166 = HTT x .83 = Mhz
150 = HTT x .75 = Mhz
133 = HTT x .66 = Mhz
100 = HTT x .50 = Mhz
What can my 210Mhz memory run in this config?
295 x .83 = 244 = not a chance
295 x .75 = 221 = not quite
295 x .66 = 195 Yes, but slow.
You have two choices, try and tighen timings and run 195 which is perfectly OK choice. Or Change CPU multiplier and start over. Ideally you want for max CPU and memory to coinside...Does'nt always work the way you want... My Ballistix below is 245Mhz stable but I'm running less for more CPU speed which always wins. You should too.
To help you along in the "consolidate" phase user
Gogar has made a niffty script found
here.
Just put in those maximuns found under the "isolate" phase and it will spit out the best choices.
After you go though these steps , take notes, you'll become more familiar with the whole tweaking process (learn by doing) and will be able to dial in better frequencies, timings, voltages, and faster too. But this should get you pretty close to safe and optimal speeds
UPDATE: Dual core CPU stability testing
X2 is not any different than a single processor overclocking but for volts and when prime testing CPU(s) for stability:
Volts should not exceed 1.45 for safe operation!
Prime95
1. Make two folders with Prime95
http://mersenne.org/gimps/p95v2413.zip
2. Starting two instances: Launch both instances from each folder and choose: torture test > small FFT's > click OK.
3. Next, launch taskmanager and set affinity of the first instance of prime to CPU 0 only. The other instance of prime to CPU 1 only.
Quick and dirty A64 clocking guide **UPDATE** X2 OC information!
