| Opteron Overclocking walkthroughs. Originally posted by James W Overclocking is really about increasing the frequency of the system bus, which is done by changing the HT clock setting (it goes by different names on different boards) in your CMOS settings. This has a number of side effects. 1) It speeds up your processor, which is 90% of the point of overclocking. Your processor's internal frequency is obtained by multiplying 2 numbers (HT clock x CPU multiplier) found in CMOS settings. The maximum CPU multiplier for your 146 is 10. At normal HT clock speed (200 MHz) your CPU will run at: 200 MHz x 10 = 2 GHz. Since you can't increase the CPU multiplier any further, the only way to increase the speed of the CPU is to increase the HT clock. Your 146 will probably go as far as 270 MHz on the HT clock (at least): 270 MHz x 10 = 2.7 GHz, but it will cause extra heat to be generated which can contribute to the chance that it will become unstable, hence the obsession with cooling around here  . If the HT clock is set too high, the processor can also become unstable because it's not being given enough time to finish its work before the next tick of the clock comes along. You need an efficient way to judge whether your CPU is stable, because the normal o/c method is to increase the HT clock in small (say 10 MHz) steps, then test the CPU for stability with something like Prime95 for twenty minutes before increasing it again. Once you hit your best HT clock speed, it's a good idea to run a battery of different stability tests for several hours 2) Another side effect of increasing the HT clock is that your DDR memory is forced to run at a higher frequency too. At normal speed DDR400/PC3200 multiplies the HT clock by 2, that's: 200 MHz x 2 = 400 MHz, hence DDR400 but 270 MHz x 2 = 540 MHz or DDR540, so you'll need to use a memory divider in CMOS settings to slow it back down to around DDR400 again. This is complicated to explain - I tried it here: http://forum.micromart.co.uk/shwmessage.aspx?forumid=29&messageid=71425#bm71719 but it's often better than the alternative of buying high speed memory. 3) Yet another side effect of increasing the HT clock is that the clock speed of the link between the processor and the chipset on your motherboard (the HT link) increases too. It's calculated with another multiplier called the HT multiplier which defaults to 5 in CMOS settings. HT multi(5) x HT clock(200 MHz) = 1000 MHz, and you should treat 1000 MHz as its maximum value. 5 x 201 MHz = 1005 MHz ie too high, so above 200 MHz drop HT multi to 4 for 4 x 200 MHz = 800 MHz above 250 MHz HT clock drop HT multi to 3 to keep link frequency below 1000 MHz. 4) Other buses like the PCI or PCI-E buses may also scale their clock speeds along with the HT clock, so you need to lock them at 66/67 MHz and 100 MHz respectively. That's as simple as I can get it without skipping over important concepts, but feel free to ask questions, and don't be afraid to take some time to learn what you're doing - it's not easy until you've got used to it and had a chance to try it out for yourself. The basic method is: 1) Lock the buses (see 4 above)
2) Increase the HT clock frequency by a small amount, maybe 5 or 10 MHz
3) Apply an appropriate memory divider (see 2)
4) Set the HT multiplier to the correct value (see 3)
5) Test for stability and watch the CPU temperatures (set 50C as your limit for now)
6) Repeat from 2) until you hit an instability or your CPU temperature threshold ******************** Originally Posted by Frosty15 The first thing you want to find out is how fast your Opteron will run without other factors (memory, multiplier) causing instability so you need to reduce the LTD setting from 5 to 3, and the memory speed (either use a ram divider set at 1:2 or manually set ram to run at 100mhz). You can now find your highest possible HTT. As you overclock you will reach a level where the cpu can't go any faster at stock voltage, you can either stop there with a mild overclock or keep pushing by increasing the voltage. If you do decide to go a little further keep an eye on your temps and stay below 55°C. You can now start overclocking, a decent application to use to check stability is Prime 95 http://www.mersenne.org/freesoft.htm : Select ‘torture test’ under ‘options’ & ‘In Place Large FFTs’ Set Prime going & leave it for at least 15 minutes. Remember - Check your CPU temperature; make sure it’s not going past the ‘safe zone’ of 55°C. Increase the HTT by 10-15mhz then reboot and run Prime95 torture test, if it's stable you can exit, reboot, enter the bios and increase your HTT again. When Prime95 becomes unstable you can either keep reducing HTT 3mhz and rre-running until it becomes stable or increase voltage. The voltage for the cpu if you choose to do so is Vcore, just keep checking your temps (DON'T EXCEED 1.65v). When you have reached your highest HTT run Prime95 for 2 hours to check your rig is fully stable, to be completely sure leave it to run overnight. If there are stability issues reduce HTT a further 3mhz and re-run, if not make a note of your settings - HTT and Vcore (if increased), now you can overclock your ram. To overclock your memory you need to use the same principles as overclocking your cpu, you want to remove the cpu from the equation to find your highest stable memory frequency without the cpu causing instability. Leave the LTD at x3 and lower the cpu multiplier to x6, this will underclock your cpu, lastly set your memory divider back to 1:1 or manually to 200mhz. Again like the cpu when your memory becomes unstable you can either reduce its frequency a little or increase the voltage. Increase the HTT 10mhz (as the ram is running 1:1 it will also increase your memory 10mhz) eg 210mhz or DDR420 A great application for testing memory stability is MemTest86 http://www.memtest86.com/ (Using Test No.5), run for 10 mins to check stability. If there are no errors load windows and use a benchmarking software app such as 3DMark05 http://downloads.guru3d.com/downloadget.php?id=874&file=4&evp=3551840ce92a9075efa0e13af2865a8f If all runs fine then exit, enter the bios and increase the HTT by 10mhz making it 220mhz or DDR440. Repeat uuntil you have errors, when errors start you can either reduce the HTT by 3-4mhz and retest or increase your Vdimm voltage by 1 increment to increase stability. When increasing the Vdimm has no effect and your memory still shows errors when testing you have 2 options. You can either reset your memory settings to their last stable settings or you can try loosening your memory timings, to be honest your memory has timings of 3-8-4-4 so there won't be much leeway here, higher grade modules have timings as tight as 2-2-2-6 which will allow a much greater variation in loosening timings. You could reduce your Command Rate from 1T to 2T and see how much of an impact on your overclock it has but it will reduce performance. When you reach your tightest overclocked settings which run stable you can then set your memory divider to suit your overclocked cpu and memory settings. Reset the cpu multiplier back to its original value (10), then adjust your memory divider to the nearest value of your memory. eg Max cpu=265mhz, Max memory=230mhz, a memory divider of 5:6 (166) will run the memory @ 220mhz.
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