Both the Athlon II X2 and the Phenom II X2 managed to overclock to about the same levels. Without any additional core voltage they were able to run at 3.5 - 3.6GHz, with the Athlon II being able to go a bit higher thanks to being free of any L3 cache. With less than 10% additional core voltage I was able to get both chips up to 3.7GHz. The Athlon II X2 250, when overvolted, managed to reliably hit 3.75GHz.

Gary's sample was able to work solid at 4.0GHz while mine would fail at 3.8GHz or above.

Processor Highest Overclock (Stock Voltage) Highest Overclock (Overvolted) % Increase over stock
AMD Phenom II X2 550 BE 3.5GHz 3.7GHz 19%
AMD Athlon II X2 250 3.6GHz 3.75GHz 25%
Intel Pentium E6300 3.40GHz 3.57GHz 28%


The Pentium E6300 topped out just under 3.6GHz with ~10% additional voltage. I noticed a strange trend when overclocking the E6300. I set the FSB to 340MHz, which when multiplied with the CPU's 10.5x multiplier should yield 3.57GHz. Yet with no additional voltage, the CPU would hardly ever go above a 10.0x multiplier once in Windows - resulting in a 3.40GHz clock speed:

The chip wasn't throttling due to heat, it simply would not run at 3.57GHz without any additional voltage. As soon as I gave it more voltage or as soon as I disabled EIST, the CPU ran at its correct frequency:

All I did was disable EIST, although increasing the VID also resulted in the same thing

Even with additional voltage however I wasn't able to get the E6300 stable at above 3.57GHz.

Processor x264 Pass 2 Cinebench XCPU Crysis Warhead
AMD Phenom II X2 550 BE @ 3.7GHz 11.0 fps 8224 74.5 fps
AMD Athlon II X2 250 @ 3.75GHz 11.0 fps 7968 75.0 fps
Intel Pentium E6300 @ 3.57GHz 11.7 fps 8096 80.8 fps


The Pentium E6300 is actually quite competitive when overclocked and appears to scale very well with additional clock speed. It also helps that AMD's clock speed advantage shrinks once we overclock these chips a bit.

Power Consumption Final Words
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  • vajm1234 - Tuesday, June 2, 2009 - link

    its really hard to believe ad a lil concern for upcoming c2d processors --- why that 6300 sample didnt overclock? wat was wrong 3.7 i xpct normally but i m amazed as its a 45nm.... not 90 or 65
  • crimson117 - Tuesday, June 2, 2009 - link

    I'm getting image not found for this first image on the last page of the review:

  • ShawnD1 - Tuesday, June 2, 2009 - link

    I like how you included the overclockability at stock voltage. Since all of my computers use stock heatsinks, overclocking at stock voltage is pretty much all I can do.
  • Gary Key - Tuesday, June 2, 2009 - link

    I used the standard heatsink off the Phenom II 940 on the X2 250, 1.4V, and hit 3.825GHz in Win7 64, idle temps around 33C, full load at 54C. I have retail CPUs coming with the new cost reduced heatsink to see what happens but any stock AM2+ heatsink from a Phenom/PhenomII works wonderfully for overclocking these two CPUs.
  • RamarC - Tuesday, June 2, 2009 - link

    I know AMD has 'nudged' mobo makers to prevent this, but some still allow it. I'm curious why Anand didn't experiment with it.
  • AnnonymousCoward - Wednesday, June 3, 2009 - link

    I figured those extra cores have defects.
  • Anand Lal Shimpi - Tuesday, June 2, 2009 - link

    It's more of a timing issue than anything else. I spent a lot of last week working on Lynnfield and there's one more CPU review before this week is up. I am curious about it and will look into it shortly though :)

    Take care,
  • flipmode - Tuesday, June 2, 2009 - link

    Hi Anand. Great review, it is much appreciated. The first thing I looked for was a comparison to the Brisbane CPU. To me, a comparison to Brisbane and a comparison to Penryn are the two most interesting.

    Just thoughts.
  • ltcommanderdata - Tuesday, June 2, 2009 - link

    I'm guessing if Phenom II X2s use harvested cores, they'll eventually be a limited commodity. Still, the Athlon II X2 seems to have a lot of scaling room left so higher clocked Athlon II X2s will probably do just as well.

    I just flipped through the benchmarks this morning, but since I was one of those commenting on wanting to see the best of dual core Netburst processors like the 965EE for comparison, I wanted to thank you for deciding to include the 955EE.
  • ltcommanderdata - Tuesday, June 2, 2009 - link

    As a follow-up is AMD still making 90nm dual cores or have they converted the fab to 45nm now? I believe the previous fastest dual core was still the 3.2GHz 90nm Athlon 64 X2 6400+. It's too bad it wasn't included here.

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