Investigations into Socket 939 Athlon 64 Overclocking
by Jarred Walton on October 3, 2005 4:35 PM EST- Posted in
- CPUs
Case and CPU Cooling
For the case, things are a bit more straightforward. The cheapest cases can still work fine for any system, though they're usually more difficult within which to work, may have sharp edges, may be noisy, and could even warp or bend. As with power supplies, you get what you pay for. We'd suggest getting a case that has at least two 120mm fan locations, one in the front of the case and one in the rear. If you use 80mm fans, you pretty much need two 80mm models to equal the flow rate of a 120mm model. Blow holes on the top, bottom and side of the case can be added if you really want, though the effectiveness varies. What you really want is to get a nice flow of air going through the case without a lot of turbulence. A single 120mm fan at the front of the case acting as an intake with a second 120mm fan at the rear blowing out is generally adequate, once you add in the PSU fan, which would also be blowing out. Going beyond that to get more air flow is possible, but you get diminishing returns and increased noise. We've seen cases with seven fans all blowing in different directions that couldn't overclock at all, so more is definitely not always better.
We used an (old) Antec SX635BII for our testing, equipped with three 80mm fans. A case with two 120mm fans like the Antec SLK3700-BQE would be a bit quieter, though we didn't focus on noise levels as part of the setup. Antec cases can be really heavy, as they're built of thick steel, but they're also easy to work within. If you plan on moving your PC around a lot or putting it on top of your desk, we'd definitely recommend getting a lighter case - perhaps a SFF might be an option, if you can afford the luxury. I've picked up the massive Thermaltake Armor with a full system installed, and it was still noticeably lighter than either the Antec SX635BII or the SLK3700-BQE. (I can't comment on which is easier to work with, as the Armor system was assembled by someone else.)
Lastly, you need a decent cooler for the CPU. The stock AMD cooler will get the job done for basic overclocking, but if you want to get above 2.3 or 2.4 GHz, you'll need better. There are many options out there right now, but unlike other components, a more expensive cooler may not actually be better. Solid copper designs cost more and should cool a bit better (due to their lower specific heat and increased mass), but there's no guarantee. For overall cooling quality at a reasonable cost, we'd go with either a Zalman CNPS7000B (either the AlCu or Cu version is fine) or else get a Thermalright XP-90 with a Panaflo 92mm M1A fan. With shipping, either option should run $33 to $45, give or take. The Zalman is probably a bit quieter and it comes with a fan speed control while the Thermalright is much easier to mount onto the CPU in our opinion.
We used the aluminum version of the Thermalright XP-90, as the copper model costs about $15 more and doesn't really improve the cooling performance much. If you have another favorite HSF, you can get that instead. During our testing - even with an X2 overclocked to 2.7 GHz - the heat sink never even became very warm to the touch. As an added bonus, on the particular motherboard that we're using, the HSF overhangs the two RAM slots that we populated, so the RAM should also get more air movement than in other designs. Sure, it makes installing and removing RAM a bit trickier, but it wasn't difficult at all.
For the case, things are a bit more straightforward. The cheapest cases can still work fine for any system, though they're usually more difficult within which to work, may have sharp edges, may be noisy, and could even warp or bend. As with power supplies, you get what you pay for. We'd suggest getting a case that has at least two 120mm fan locations, one in the front of the case and one in the rear. If you use 80mm fans, you pretty much need two 80mm models to equal the flow rate of a 120mm model. Blow holes on the top, bottom and side of the case can be added if you really want, though the effectiveness varies. What you really want is to get a nice flow of air going through the case without a lot of turbulence. A single 120mm fan at the front of the case acting as an intake with a second 120mm fan at the rear blowing out is generally adequate, once you add in the PSU fan, which would also be blowing out. Going beyond that to get more air flow is possible, but you get diminishing returns and increased noise. We've seen cases with seven fans all blowing in different directions that couldn't overclock at all, so more is definitely not always better.
We used an (old) Antec SX635BII for our testing, equipped with three 80mm fans. A case with two 120mm fans like the Antec SLK3700-BQE would be a bit quieter, though we didn't focus on noise levels as part of the setup. Antec cases can be really heavy, as they're built of thick steel, but they're also easy to work within. If you plan on moving your PC around a lot or putting it on top of your desk, we'd definitely recommend getting a lighter case - perhaps a SFF might be an option, if you can afford the luxury. I've picked up the massive Thermaltake Armor with a full system installed, and it was still noticeably lighter than either the Antec SX635BII or the SLK3700-BQE. (I can't comment on which is easier to work with, as the Armor system was assembled by someone else.)
Lastly, you need a decent cooler for the CPU. The stock AMD cooler will get the job done for basic overclocking, but if you want to get above 2.3 or 2.4 GHz, you'll need better. There are many options out there right now, but unlike other components, a more expensive cooler may not actually be better. Solid copper designs cost more and should cool a bit better (due to their lower specific heat and increased mass), but there's no guarantee. For overall cooling quality at a reasonable cost, we'd go with either a Zalman CNPS7000B (either the AlCu or Cu version is fine) or else get a Thermalright XP-90 with a Panaflo 92mm M1A fan. With shipping, either option should run $33 to $45, give or take. The Zalman is probably a bit quieter and it comes with a fan speed control while the Thermalright is much easier to mount onto the CPU in our opinion.
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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