Investigations into Socket 939 Athlon 64 Overclocking
by Jarred Walton on October 3, 2005 4:35 PM EST- Posted in
- CPUs
System Settings
We have a bunch of screenshots from CPU-Z showing the CPU and Memory tabs, covering most of the settings that we used. Rather than linking 44 images, though, we're just going to provide a single Zip file of all the screens. One thing that became immediately clear is that the BIOS voltages were almost never reflected in the CPU-Z results. Which one is more accurate is impossible to say, short of busting out a voltmeter (and knowing where to attach it).
We did not remember to get a screenshot of every single configuration tested, since we went back to fill in the blanks on CPU performance after running the initial benchmarks. However, you can get the settings used in the following table. If you have a motherboard that doesn't support the same settings that we used, you may or may not be able to reach a specific overclock.
Disclaimer: Many of the tested voltages on the CPU are probably higher than necessary. After trying for 10x280 with up to the maximum voltage possible from the motherboard, I was probably a bit too lenient on turning voltages back to normal. These are more or less the settings I used during the testing - there may be a few errors in record keeping. If you are looking for long-term stability and you can get the system to run stable at 1.450V instead of 1.650V, that would be a wise decision. The results in the following table are merely intended as an initial reference point.
Note how CPU voltages scaled rapidly as we neared the highest overclock levels. We didn't spend a lot of time trying to get things running stably at a lower voltage level, so mostly, we went in .05V increments - again, you might be able to get better results. If we experienced a crash during our benchmarking, we would try to increase the CPU and/or chipset voltage to get the tests to run stable. If that didn't work, we resorted to tweaking memory timings, generally by increasing latencies until we found a stable setting. Once we went from CL2 to CL2.5, we didn't spend the time trying to get 2.5-2-2, 2.5-3-2, or anything other than 2.5-3-3 (or higher latencies) to run stably.
With our performance RAM, we kept it at a steady 2.8V setting. We did try 2.9V on some of the higher overclocks, particularly where we had to drop from the PC3200 to PC2700, but we couldn't get 1T timings at PC3200 above a 280 MHz CPU bus speed. The value RAM was kept at a steady 2.6V setting and 2.5-3-3-8-1T timings, except in a few cases where we had to run with 2T timings. We tried to get 3-4-4-8-1T instead, but at 9x300, we could not run the value RAM without the 2T setting.
You'll notice the "crash" and "unstable" comments on several of the highest overclock attempts. "Crash" means that we were unable to run many of the tests due to repeated lockups, reboots, etc. "Unstable" means that we were able to get benchmark results for all (or nearly all tests), but programs might crash at times. For example, Far Cry might crash at 1024x768 4xAA on the first attempt, but rebooting and starting again from that point would complete the tests. We tried to run all of the gaming benchmarks in order without rebooting, which will keep system temperatures higher than letting the GPU cool down for a couple of minutes while we reboot. We won't include the settings that crashed in our results, but we did include the unstable results. We'll be using these unstable settings for some cooling tests in the future to see if a change in HSF will help - and hopefully even allow higher overclocks.
A last comment is that we didn't fully benchmark all of the settings listed in the charts. We tested 1800, 2000, 2200, 2400, 2600, and 2700 MHz. We also tested 2800 MHz on a couple of configurations, although stability was iffy at best. In order to provide a linear scale (so that the results at 2700 aren't skewed), we interpolated the in-between scores. This is a problem with the graphing capability that we have within Excel. We did run some quick tests at each setting, though, just to verify that we could POST and complete PCMark04/PCMark05. In case you're wondering, the entire benchmark suite takes around 4 to 5 hours to complete. That will hopefully explain why we didn't run the additional tests or spend a lot of time fine-tuning each tested setting.
And now, on with the benchmarks.
We have a bunch of screenshots from CPU-Z showing the CPU and Memory tabs, covering most of the settings that we used. Rather than linking 44 images, though, we're just going to provide a single Zip file of all the screens. One thing that became immediately clear is that the BIOS voltages were almost never reflected in the CPU-Z results. Which one is more accurate is impossible to say, short of busting out a voltmeter (and knowing where to attach it).
We did not remember to get a screenshot of every single configuration tested, since we went back to fill in the blanks on CPU performance after running the initial benchmarks. However, you can get the settings used in the following table. If you have a motherboard that doesn't support the same settings that we used, you may or may not be able to reach a specific overclock.
Disclaimer: Many of the tested voltages on the CPU are probably higher than necessary. After trying for 10x280 with up to the maximum voltage possible from the motherboard, I was probably a bit too lenient on turning voltages back to normal. These are more or less the settings I used during the testing - there may be a few errors in record keeping. If you are looking for long-term stability and you can get the system to run stable at 1.450V instead of 1.650V, that would be a wise decision. The results in the following table are merely intended as an initial reference point.
Click to enlarge.
Note how CPU voltages scaled rapidly as we neared the highest overclock levels. We didn't spend a lot of time trying to get things running stably at a lower voltage level, so mostly, we went in .05V increments - again, you might be able to get better results. If we experienced a crash during our benchmarking, we would try to increase the CPU and/or chipset voltage to get the tests to run stable. If that didn't work, we resorted to tweaking memory timings, generally by increasing latencies until we found a stable setting. Once we went from CL2 to CL2.5, we didn't spend the time trying to get 2.5-2-2, 2.5-3-2, or anything other than 2.5-3-3 (or higher latencies) to run stably.
With our performance RAM, we kept it at a steady 2.8V setting. We did try 2.9V on some of the higher overclocks, particularly where we had to drop from the PC3200 to PC2700, but we couldn't get 1T timings at PC3200 above a 280 MHz CPU bus speed. The value RAM was kept at a steady 2.6V setting and 2.5-3-3-8-1T timings, except in a few cases where we had to run with 2T timings. We tried to get 3-4-4-8-1T instead, but at 9x300, we could not run the value RAM without the 2T setting.
You'll notice the "crash" and "unstable" comments on several of the highest overclock attempts. "Crash" means that we were unable to run many of the tests due to repeated lockups, reboots, etc. "Unstable" means that we were able to get benchmark results for all (or nearly all tests), but programs might crash at times. For example, Far Cry might crash at 1024x768 4xAA on the first attempt, but rebooting and starting again from that point would complete the tests. We tried to run all of the gaming benchmarks in order without rebooting, which will keep system temperatures higher than letting the GPU cool down for a couple of minutes while we reboot. We won't include the settings that crashed in our results, but we did include the unstable results. We'll be using these unstable settings for some cooling tests in the future to see if a change in HSF will help - and hopefully even allow higher overclocks.
A last comment is that we didn't fully benchmark all of the settings listed in the charts. We tested 1800, 2000, 2200, 2400, 2600, and 2700 MHz. We also tested 2800 MHz on a couple of configurations, although stability was iffy at best. In order to provide a linear scale (so that the results at 2700 aren't skewed), we interpolated the in-between scores. This is a problem with the graphing capability that we have within Excel. We did run some quick tests at each setting, though, just to verify that we could POST and complete PCMark04/PCMark05. In case you're wondering, the entire benchmark suite takes around 4 to 5 hours to complete. That will hopefully explain why we didn't run the additional tests or spend a lot of time fine-tuning each tested setting.
And now, on with the benchmarks.
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JarredWalton - Monday, October 3, 2005 - link
It's tough to say how things will pan out long-term. 1.650V seems reasonably safe to me, but I wouldn't do it without a better HSF than the stock model. The 1.850V settings made me quite nervous, though. If you can get your CPU to run at 1.600V instead of 1.650V, that would be better, I think. There's also a possibility that slowing down your RAM slightly might help the CPU run at lower voltages. I'd sacrifice 5% to run what I consider a "safer" overclock, though really the thought of frying a $140 CPU doesn't concern me too much. That's less than any car repair I've had to make....cryptonomicon - Monday, October 3, 2005 - link
well for most overclocks a reasonable ("safe") increase of voltage is 10-15%. however that is just a guideline, it may be more or less. there is sort of a way to find out: if you work on overclocking to the maximum of your chip while scaling the voltage, you will eventually hit a place where you have to increase the voltage dramatically just to get up the next FSB bump. for example if you are at 2500mhz and 1.6v, then it takes 1.75v just to get to 2600mhz, then you have hit that boundary and should go back down immediatly. when the voltage to cpu speed ratio is scaling consistently, then things are fine. but once the voltage required becomes blatently unbalanced, that is the logical time to stop... unless you have no concern for the longetivity of the chip.Ecmaster76 - Monday, October 3, 2005 - link
Finally goaded me into overclocking my P4 2.4c. I had been planning for a while but never bothered too.So I got bored and set the FSB to 250mhz (I went for my goal on my first try!) with a 5:4 (still DDR400) memory ratio. It works great at stock cooling + stock voltage. I will have to do some long term analysis of stability but since I am building a new system before the years end I don't really care if it catches on fire. Well as long as it doesn't melt some of my newer nerd toys that are attached to it.
lifeguard1999 - Monday, October 3, 2005 - link
I am running an AMD Athlon 64 3000+ Processor (Venice) @ 2.7 GHz, stock HSF; 1.55V Vcore; DFI LANPARTY nF4 SLI-DR. It was cool seeing you run something similar to my setup. I run value RAM and it seems that I made the right choice for me (giving up at most 5% performance). You ran at Vcores much higher than I do, so it was interesting to see the CPU handle that.The only thing I would add to this article is a paragraph mentioning temperatures that the CPU experienced.
mongoosesRawesome - Monday, October 3, 2005 - link
yes, i second that. temps at those volts using your cpu cooler as well as with maybe a few other coolers would be very helpful. also, if you could do a few tests using different coolers to see when temps hold you back.JarredWalton - Monday, October 3, 2005 - link
I've got some tests planned for cooling in the near future. I'll be looking at CPU temps for stock (2.0 GHz) as well as 270x10 with 1.750V. I've even got a few other things planned. My particular chip wouldn't POST at more than 2.6 GHz without at least 1.650V, but that will vary from chip to chip. The XP-90 never even got warm to the touch, though, which is pretty impressive. Even with an X2 chip, it barely gets above room temperature. (The core is of course hotter, but not substantially so I don't think.)tayhimself - Tuesday, October 4, 2005 - link
Good article, but your Vcore seems to scale up with most of the increments in speed? Did you HAVE TO raise the vcore? Usually you can leave the vcore until you really have to start pushing. Comments?JarredWalton - Tuesday, October 4, 2005 - link
2.20GHz was fine with default 1.300. 2.40GHz may have been okay; increasing the Vcore to 1.40V seemed to stabilize it a bit, though it may not have been completely necessary. 2.60GHz would POST with 1.450V, but loading XP locked up. 1.550V seemed mostly stable, but a few benchmarks would crash. 2.70GHz definitely needed at least 1.650V, and bumping it up a bit higher seemed to stabilize it once again. 2.80GHz was questionable at best even at 1.850V with the current cooling configuration. It wouldn't load XP at 2.80GHz at 1.750V, though.JarredWalton - Tuesday, October 4, 2005 - link
My memory on the voltages might be a bit off. Personal experimentation will probably be the best approach. I think I might have erred on the high side of required voltage. Still, past a certain point you'll usually need to scale voltage a bit with each bump in CPU speed. When it starts scaling faster - i.e. .1V more to get from 2700 to 2800 MHz - then you're hitting the limits of the CPU and should probably back off a bit and call it good.tayhimself - Tuesday, October 4, 2005 - link
Thanks a lot for your replies. Looks like there is a fair bit of overclocking even if you dont increase the Vcore too much to help save power/noise etc.Cheers