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CPU temperature fluctuations? Athlon X2 3800+ 939.

Last response: in CPUs
August 30, 2006 1:43:09 AM

I recently bought an Athlon X2 3800+ for my new socket 939 motherboard. I put on some Arctic Silver and popped it in.

My case has pretty good cooling, and on my old Athlon 3400+ (socket 754) I idled at 28C and peaked around 42C. With my new processor, I've seen the temperature get as low as 24C, but then sometimes it gets as high as 52C. Is such a huge fluctuation in temperature normal?

Right now it's at 40C, and all I'm doing is using Winamp, Firefox, and AIM.
August 30, 2006 2:29:22 AM

speaking firsthand, the processor does seem to run fairly warm on average... though my case doesnt have ideal cooling (pretty much only the gpu, psu, motherboard chipset, and cpu fans are on), ive tried to remove as much heat from other components as i could, by disabling and powering them down and such... dont have more fans on because it gets wayyyyy too noisy then

not ocd with stock hsf and AC5 applies... mine has been down to about 31-33C idle in the morning (around winter, lol)... typically at 47C with CnQ, idle 51C without CnQ... and 100% full load at 60C+... ...the chip does seem to run fairly hot, even with a dab of AC5 applied... all i can suggest, is to wait a week or 2 to let the AC5 settle in, your cpu temperatures should drop about 3-5C or so then, compared to with oem thermal paste... also, a 3rd party hsf might be advisable too... and even better airflow in general, even though you said your case has good cooling... ...either way though, your X2 s939 cpu can take up to about 65-67C before you have any issues with stability

you can try reseating the cpu hsf also, if the hsf itself isnt seeming warm at all, when your cpu is heating up

all in all though, you temperatures dont seem to be a problem
August 30, 2006 2:33:05 AM

So 52C isn't anything to really worry about? I have a 250mm intake on the side of the case and two 80mm's and one 120mm exhaust in the back.

I've heard a lot about the 3800's success with overclocking, so I assumed at stock speeds it would have a nice temperature.
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August 30, 2006 2:42:39 AM

yeah, 52C isnt a problem, if thats the highest temperature its getting to...

its only an issue when the temperatures get into the mid 60s, as long as you can stay below 60 ideally, nomatter what speed youre at, youll be okay

as far as OCing, yes... the chip does OC very well... stock it runs at 2.0GHz as you know, ive been able to push mine up to 2.71GHz on stock air cooling (didnt try for higher, because of cooling issues specifically, plus the hsf got VERY noisy then too, and that certainly wasnt much fun to listen to constantly)... 2.4GHz (the same as an X2 4600+) is usually very easily attainable... you dont need to change voltages at all to reach that even... but, as long as you know know how to OC, and vary your HTT multiplier, voltages, and memory speed and timings accordingly, you should do okay then (be sure to watch your temperatures though too)... to a lesser extent, the motherboard matters for OCing, but you should do okay with reaching 2.4GHz though either way

also, as far as temperatures when comparing single core and multi core cpus... multiple cores will naturally run hotter than a single core of the same or similar clock speed, especially under load
August 30, 2006 2:55:50 AM

Any advice for OC'ing it? I have a DFI LANParty UT Ultra-D, so I don't think the motherboard will have many limitations. I've overclocked before by just changing the vcore and clock speeds, but I've never tried messing with memory timings or frequency or anything like that.

I don't feel the need to go to the point of upping the voltage on this chip though, as it's pretty much as fast as I need it to be as it is. I don't want to risk making it too hot. I wouldn't mind seeing how far I can get on the stock voltage, though.
August 30, 2006 3:06:38 AM

well, for OCing, the first thing is to reduce your HTT multiplier from 5X, down to 3X (that way you dont overshoot the 2000MHz boundry from OCing, even a multiplier of 4x may be okay if its only a minor OC, its basically cpu FSB x HTT multiplier = HTT speed x 2, so you would ideally want to stay under 2000MHz either way)... the second is to reduce your memory speed, such as if its at 200MHz, reduce it down to 166MHz instead, because when you raise the cpus fsb speed, youll simultaneously be raising the memory speed by the same amount as well... and if your memory cant OC very well, youll run into problems then... the third thing is to relax your memory timings if you run into problems booting and such (or even other issues), if theyre at 2.5-3-3-5... maybe relax them up to 3-5-5-7 or so (or higher)... for voltages (this part is actually what you would need to worry about, more than temperatures, cuz you can overvolt components and fry them if you go too high)... the cpu defaults to 1.4V... raising it up to 1.5V is usually pretty safe to do, but the higher you go, again, the more you risk damaging it... ...for memory, the default i believe is 2.63V... raising to 2.7V is usually pretty safe as well... some people shoot up to 2.9V for their memory... ...but either way, better safe than sorry in that respect, and i personally dont feel raising the voltages should be done, unless you really need to, i personally prefer to run at reduced voltages when i can... my memory is actually running at 2.55V (the lowest it can go on my MB)

also, some people run into issues with OCing when CnQ is enabled, disabling CnQ then might be necessary... personally i havent had any issues with it when OCing, but just in case

also, as a side note... make sure you download the appropriate dual core cpu drivers and optimizations from amds site if you havent done so already... those dramatically help increase performance
August 30, 2006 3:34:52 AM

what you are seeing is AMD's cool n quiet software doing its job.when you are not using it for heavy tasking,the multiplier is lowered so that the cpu runs cooler.however when you put the processor under extreme load,the multiplier is automatically adjusted to max.hence the reason you see a higher temp.and 52 degrees celcius is not overly hot when the cpu is under full load.and yes the X2 3800+ makes a great over clocker.oh one more thing.before you overclock,you need to go ito your bios and disable the cool n quiet,otherwise you will have all kinds of problems.


X2 4400+@2.4
August 30, 2006 3:56:26 AM

So you're suggesting lowering the multiplier and upping the FSB to end up with the same clock speed of 2000mhz?

If I lower the multiplier to 3 I'd have to increase FSB to 333 to equal 2000mhz (or 1998mhz anyway). Is that possible on stock voltage? And what kind of performance increase will that result in?
August 30, 2006 4:04:44 AM

well, you dont have to stay at 2000MHz HTT, you can stay at anything below it without a problem too, you wont incur any performance penalties either (it would mainly only be relevant to server setups that have 8 cpus or more, or so, so a lower HTT speed is okay to run at without a problem)... i was only saying to reduce the multiplier, to ensure that your computer can boot, as HTT is only designed to run at up to 2000MHz, some motherboards can go 100MHz higher, but usually not... and as to why some people would want to increase it, i dont know... you wont benefit from it, maybe bragging rights i guess

so, you absolutely do not have to stay at 2000MHz... you can run just fine at 1200MHz HTT speed if you wanted to i believe (200MHz cpu FSB x 3X HTT multiplier = 600MHz HTT speed x 2)... its only to ensure that you dont go over by accident, and end up not being able to boot your computer, and having to reset the cmos battery... HTT multipliers of 2X and 1X arent advisable, you wont be able to boot using them either im sure

yes, its definetly possible to do on stock voltages, as theyre not relevant to the HTT multiplier

edit: oops... i think i misread, maybe... ...hmmm, well... should think of hypertransport speed, and cpu fsb speed as two different things... ...which can both be affected by the hypertransport multiplier... if that makes any sense... ...the cpu fsb speed does not have a limit (per say)... but the hypertransport speed, does however, its limit is 2000 MHz

why they refer to the cpu as having a fsb, i dont know either, maybe just a way to indicate cpu speed... as the s939 motherboards dont even have a fsb... instead using the hypertransport bus (instead of the front side bus, like intels cpus use)

i suppose im only confusing things though... lol

BUT, lowering the HTT multiplier, is only necessary if you plan on increasing your cpu speed at all... an example is, at default, with a cpu speed of 2000MHz... your cpus fsb speed would then be 200MHz x 5X HTT = 1000MHz HTT speed x 2 = 2000MHz HTT speed (the x 2 is due to it being DDR)... ...or, if you wanted your cpu speed to be 2400MHz, you would then do 240MHz cpu FSB x 4x HTT = 960MHz HTT speed x 2 = 1920MHz HTT speed... and it works just fine then even still, no performance penalty... ...but, if you did 240MHz cpu FSB x 5x HTT = 1200MHz HTT speed x 2 = 2400MHz HTT speed... you wouldnt be able to even boot your computer, guaranteed

also, i dont know if you can even reach 333MHz CPU FSB speed anyhow... not without some serious cooling, and even then

i also forgot about the cpu multiplier... duh, lol... THATs what indicates the cpu speed, i was like, something doesnt sound right... so, the the HTT multiplier determines the HTT speed, and the CPU multiplier determines the CPU speed... the default CPU multiplier is 10x... so at a cpu FSB of 200MHz x 10x cpu multiplier, you then have 2000MHz cpu speed... a cpu FSB of 200MHz x 5x HTT multiplier = 1000MHz HTT x 2 = 2000MHz HTT speed... ...that makes more sense then, lol... so forget the part where i mentioned the HTT multiplier affecting both the cpu speed and htt speed... it only affects htt speed, but the htt speed is based on the cpu fsb speed

and, as far as 333MHz CPU FSB then, you would take 333MHz cpu FSB x 10x cpu multiplier = 3330MHz cpu speed, so, yeah... and, that speed i dont think has even been attained at all on s939, aside from with liquid nitrogen cooling maybe