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Written by Hank Tolman   
Friday, 02 July 2010
Table of Contents: Page Index
Features and Specifications
Closer Look: Athlon-II X4-640
Testing and Results
EVEREST Benchmark Tests
Passmark PerformanceTest
PCMark Vantage Benchmark Tests
SiSoftware Sandra
Cinebench R11.5 Benchmarks
Video Game Benchmarks
AMD Athlon-II Overclocking
AMD Athlon-II X4 Final Thoughts
ADX640WFGMBOX Conclusion

AMD Athlon-II Overclocking

Now let's get into overclocking. Since the Athlon-II X4-640 is not a black edition CPU, I couldn't increase the multiplier to overclock it. Still, while the multiplier is stopped out at x15, it is important to note that it can still be decreased down as far as x4. Because of this, it is possible to decrease the multiplier and increase the bus speed and voltage and still maintain and stable overclock. To start off, however, I wanted to see how far I could get with the overclock of the Athlon-II X3-445 by just increasing the bus speed. Using the ASUS M4A785TD-M EVO, I started at 225MHz on the bus speed and increased by 5 until I couldn't boot into Windows. I was able to reach 250MHz before the Auto voltage setting didn't give me enough power to boot the system, but the overclock wasn't stable enough to withstand stressing. After increasing the voltage to 1.55V, I was able to get to 255MHz. This time it withstood the stressing like a champ, giving us our most stable overclock at 3.8GHz.


With the Athlon-II X4-640 at 3.8GHz, we achieved a 21% increase in core speed using just air to cool it. I tried getting even higher by dropping the multiplier down as far as x13.5 and increasing the bus speed above 300MHz, but I wasn't ever able to achieve a stable setting higher than the 4.1GHz I had already reached. All of my overclocking was done with air cooling only using the Scythe Mugen II CPU Cooler.

Before ending up at the 255MHz bus speed magic number, I was able to make it into windows and begin stressing the CPU at even higher speeds. Originally, I thought I had found a stable overclock as high as 3.99GHz with the bus speed set to 266MHz. Running the stressing procedure I mentioned above usually weeds out any unstable overclocks and I am able to perform testing after that. Even so, with the bus speed at 266MHz and the voltage at 1.54V, as you can see in the screenshot below, I got through all the stressing and was ready to start testing.


When I began the testing with the X4-640 at 3.99GHz, everything went fine. It wasn't until about halfway through the PCMark Vantage tests that I started having problems. The computer crashed at that point and restarted. I was a little confused by that, so I ran the stress testing procedures again. Within an hour, the overclocked failed stressing. I pushed up the voltage as high as 1.60V to see if that would help the CPU withstand stressing at the same high bus speed. It didn't work. At 3.99GHz, the processor could not again hold up to stressing. I moved the bus speed down 1MHz at a time until I ended up back at 255MHz and the processor once again withstood the stressing.

Even when using two different processors of the same make and model, or two of the same motherboard, they will likely result in different abilities as far as overclocking is concerned. While I was able to reach an overclock of 3.8GHz with air cooling, I highly encourage anyone to try out their own methods, especially with an entry-level quad-core CPU such as the X4-640. The mechanics of overclocking have more to do with the amount of voltage I can safely send to the CPU or through the northbridge. With the testing motherboard being an entry-level product itself, it doesn't have a MOSFET heat sinks or even that large of a heatsink on the northbridge. Overall, I was not disappointed by the overclock I was able to achieve at 3.8GHz. I hope you will all take the time to (carefully) test your own hardware to see how far you can safely stretch it. It certainly is a lot of fun.



# RE: AMD Athlon-II X4-640 CPU ADX640WFGMBOXRobert17 2010-07-02 15:38
I replaced an Athlon x2 4200+ I'd been using for years with an x4 930 using the same ASUS M3N78 Pro motherboard, mainly to encode audio a little faster. $99 has been the tag on the 930 for months and I found it to be a nice uptick for my needs. It seems the 940 you reviewed would be a nice upgrade for anyone with a modest budget. I agree with your article wholeheartedly. Nicely done.
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# What I would like to seeBernardP 2010-07-05 10:13
Maximum overcl#ing at maximum voltage is of limited practical use. Data I would like to see even more are: maximum overclocking at stock voltage and undervolting results at standard clock.
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# Stock Voltage OverclockHank 2010-07-14 15:30
The highest stable overclock I was able to achieve using stock voltage was 3.69GHz. I increased the bus speed to 246 and left the multiplier at x15. I haven't yet tried to see how much I can undervolt the CPU at stock speeds, but I will try it out tomorrow.
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# UndervoltingDevius 2010-07-07 06:21
BernardP: I have an Athlon II X4 630 and the same motherboard used in this review and I found the cpu to be stable with 1.21375V at stock speed.
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# Power saverAdam Smith 2010-07-15 06:44
I chose a motherbd and CPU to get he most bang for the $ using less electricity. I was going to underclock to reduce power usage. Weeks of reading lead to choosing the Athlon IIx4 635, Asus M4A89GTD PRO/USB3. It uses less electricity is very adjustable (& will do 6 cores) has 4290 GPU usb3 SATA 6 Gb/s g.skill ddr3 1.35volt 2gb x2 use win 7Pro64t. (turn ACHI on before installing windows, then do the SSD)
Typing this on the internet - my kill a watt says my power usage is 73.9 watts this includes my power adaptors for my dsl router and my monitor + KVM + an ocz vertex2 (the 2 is very important) 50G ssd (the 50 is better than the 60 for reliability+longevit y sake).
When I turn on the speakers my pwrusage goes up to 76.6. When I add my printer idle it goes up to 85 watts.
After much testing I am now at stock speeds and just turned the cpu voltage down to 1.2 and the memory voltage down. The system is very stable at these speeds.
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# Power usage on your Athlon II 635Bob 2011-04-10 13:47
Hi Adam, have you used your kill-a-watt to measure only the PC (without monitor, KVM, and other itmes)? I am really curious about this measurement.

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# RE: power saverSunji 2010-12-19 17:13
ive chosen station very similar to your configuration. funny, i read this article after buying new pc but i see we made almost the same solution.
right now i got Athlon II x4 640, Asus M4A89TD PRO mainboard, ddr3 1600 2x2 GB RAM with 1,7-1,9V. instead of onboard GPU ive chosen Gigabyte's GF GTX 460 768 OC GPU - its high-end but doesnt use much power while iddle running.
as i can tell u dont have to decrease the multiplier. while cool n quiet turned on it decrease it automaticly down to x4 with 800 MHz core speed and 1,044 Voltage. the same goes with other componetns, the system reduce usage power and increase it when its needed (i.e. when ur playing games).
the only one thing u should remember - make sure to buy better quality(80+) PSU, like Seasonic or Tagan. with my config the 520W PSU runns perfectly
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# mere curiosityADI 2011-02-02 02:55
Great article i must say... n thanks to mr. tolman. But sir there is a question which i have i dunno how correct i am in asking this but which one is better Athlon X4 640 or Phenom II X4 955 BE. X4 645 is prices at around $110 and X4 955 BE at around $150 but i was just comparing the scores of few benchmarks from different articles on benchmark reviews and found both the processor's performance is almost the same or sometimes X4 640 beating the X4 955 BE... I dunno if anyone has noticed this earlier or my observation is wrong.

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# Athlon II x4 640 vs Phenom II x4 955Andrzej 2011-09-20 12:17
Phenom II X4 955 BE is a much faster cpu than Athlon X4 640 but uses at default speeds 20 - 30W of power more both idle and under load.
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# there is a lvl 3 cache on propustheunlocker 2011-10-21 10:45 m-d4dhc88.jpg

take a look at the cache of my Athlon II x4 640 :)
runs absolutely stable and well.
at 3 Ghz, not overclocked, i had the same test result with the Phenom II x4 940
actually... they are the same.
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# amd athlon ii x4 640Dee P.I. 2012-01-30 13:10
my processor when i bought it the multiplier was x4 only is this normal???my processor is amd athlon iix4 640..need some answers pls!help
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# adm athalon x 2 640 3.20ghz 3gb memmorymichele 2012-03-04 11:28
i have this...have to say i am not impressed. it runs ok when browsing the internet. but when i need to use a program, such as photoshop or 3max, it runs supper slow. i had a pentium 4 3.0 with 5gb memmory which was 7 years old when it broke down...even till the very last of its time, the pentuim ran my programs faster and smoother than the athalon x2.
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# OppsPoxer 2012-10-02 13:12
I know you most likely(& hopefully) have this fixed by now. But in case anyone have the same issue try upgrading BIOS to begin with. Look at the motherboards manufacters specifications, does it support your processor? Clear CMOS.

Hank, I think you should add that you not only increased the bus but hopefully reduced the HT multiplier etc as well. For those less experienced.

If I remember correctly things get troublesome above 2,5Ghz HT on that MB maybe could be fixed by changing volts here and there but yeah. And that BIOS is a hell :P I want numbers updated directly. For example if you increase the bus then change the multiplier it will not (in BIOS) show what you actually change to but what it would have been with default bus freq.
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