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Overclocking

AMD Unleashed: Four CPUs, Two GPUs, All Overclocked
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In order to truly squeeze performance from each of these processors, we pushed them hard and were willing to use up to 1.55 V for the Phenom IIs if the Xigmatek cooler could keep load temps from going much above 50 degrees Celsius. Apart from pushing the northbridge frequency, the limits were already widely known for three of the processors.

When it was time to overclock the new Phenom II X3 720 BE, I eagerly started to raise the multiplier, hoping it would even surpass the high marks the Phenom II X4 940 BE set. But when stability testing at 3.4 GHz quickly resulted in a blue screen (suggesting that we had already exceeded the limits at stock voltage) hopes diminished into a hunch that this particular chip was not going to be as stellar an overclocker. 

Along the way, the Phenom II X3 720 BE required a voltage boost one-half multiplier (100 MHz CPU core speed) lower than the Phenom II X4 940 BE. For instance, reaching 3.6 GHz required 1.45 V with this chip versus the 1.40 V required for the previously-tested Phenom II. Final hopes of a higher-than-average overclock were crushed when the chip simply lost stability at 1.525 V and above. 

With a sweet spot of about 1.5 V, the chip initially passed 30 minutes of Prime95 stability testing at 3.7 GHz (18.5 * 200). In the end, we learned that it was not completely stable above 3.67 GHz (18 * 204). From there, the northbridge multiplier was raised to 12 resulting in a northbridge frequency of 2,449 MHz, and the HyperTransport (HT) was set back to its stock multiplier. The DDR2-1066 modules from Corsair did not require additional voltage for this small memory overclock.

In the CPU-Z memory screenshots, you may have noticed we were using unganged mode with each processor. Ganged mode is often the default BIOS setting and is considered to be better for single-threaded applications, while unganged can provide better performance in multi-threaded applications. Some initial testing was performed in both modes, with results indicating that neither really provided a large overall advantage. Unganged mode offered a slight edge in applications and games, while ganged mode took a few wins and provided much higher memory bandwidth scores in the Synthetic Sandra VII benchmark. So, while there may be specific applications for which one mode provides a real advantage over the other, overall, at least in our tests, effects are minimal.

As in our SBM series, the graphics cards were overclocked. We also sought to use the same GPU and GDDR5 frequencies that we used in the last round of $1,250 and $625 SBM PCs. The closest available GPU setting for the Radeon HD 4870 X2 was 782 MHz, which was 2 MHz higher than what Catalyst Control Center (CCC) allowed for the Sapphire Radeon HD 4870 X2. The memory was run at 950 MHz GDDR5, which was identical to the overclocked $1,250 PC’s memory speed.

However, this Radeon HD 4870 had a GPU core limit of 790 MHz in CCC, which was 15 MHz less than the Sapphire Radeon HD 4870’s core limit in the $625 PC SBM. Attempts were made to attain a clock speed of 805 MHz with Riva Tuner, and while the GPU didn’t artifact, the overclocking didn’t seem to stick, and performance occasionally throttled back to stock speeds during testing. In the end, we had to go with CCC, attempting to make up for the lower GPU frequency by running the GDDR5 at 950 MHz versus the 930 MHz with which our Sapphire card topped out.

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  • 5 Hide
    radguy , June 1, 2009 7:14 AM
    So did I miss somthing or where does it say what each of these processors is overclocked to. I get that the p2 x3 720be is at 3.67 but what about the rest of them. Am I missing it somewhere (very possible) or do I have to look back at your previous articles to figure it out? shouldn't that be on the test systems and configuration page. I am trying to sort through the data.
  • 2 Hide
    dirtmountain , June 1, 2009 7:30 AM
    Nice article Paul and some exhaustive work! Don't overlook the 780G/SB710 that also feature ACC for a price of $72
    http://www.newegg.com/Product/Product.aspx?Item=N82E16813157154
    making the Phenom2 x3 720 a viable option in the SBM budget category. I'm also going to be curious about the new Phenom2 x2 and Athlon2 x2 processors that are coming out June 2nd.
  • 0 Hide
    apache_lives , June 1, 2009 7:35 AM
    Has anyone noticed the benchmarks for the i5's on anandtech yet?
  • 1 Hide
    nerrawg , June 1, 2009 8:32 AM
    Great article guys - love the comparisons to the SBM machines - really gives some insight into CPU and GPU scaling and how much to spend on your processor versus your graphics for gaming builds. Thanks!
  • 8 Hide
    Sihastru , June 1, 2009 8:37 AM
    apache_livesHas anyone noticed the benchmarks for the i5's on anandtech yet?


    I did. Considering the pricing scheme of the i5 (so close to AMD) and it's high performance numbers (so close to the i7) AMD is in big trouble.

    Intel will shift all the processors that are now under the i7 (even if the 920 is rumored to become EOL, one step down on it's portfolio, which means high end Intel dual cores, will go into or under the mainstream, where AMD already has a hard time.

    This doesn't make me very happy, even if I am an Intel fanboy. Aggressive pricing schemes are overrated. AMD needs something new. Now.
  • 1 Hide
    DjEaZy , June 1, 2009 8:52 AM
    ... BIG THX to the Tom's crew... was not so hard after all? ... now, thx to YOU, we have a info about intel, nVidia and AMD/ATi solutions... how they stack up in price/performance/cost of ownership... NICELY DONE!!!
  • 5 Hide
    erdinger , June 1, 2009 9:30 AM
    Yes thanks, many people complained in the system builder marathon and you listened to the complaints... great.
  • 3 Hide
    ufo_warviper , June 1, 2009 9:35 AM
    The E5200 seems to hold up a bit better than I previously thought, an incredible value for
  • 0 Hide
    SpadeM , June 1, 2009 10:52 AM
    sihastruI did. Considering the pricing scheme of the i5 (so close to AMD) and it's high performance numbers (so close to the i7) AMD is in big trouble.Intel will shift all the processors that are now under the i7 (even if the 920 is rumored to become EOL, one step down on it's portfolio, which means high end Intel dual cores, will go into or under the mainstream, where AMD already has a hard time.This doesn't make me very happy, even if I am an Intel fanboy. Aggressive pricing schemes are overrated. AMD needs something new. Now.


    AMD doesn't need something new now, they are going to flood the market with low to mid range processor (see computex in a couple of days) that will cater to the masses. On the high end side of things the PII remains an options since it's direct competitor, the intel penryn quads will fade out to be replaced by the new kid on the block, the i5. As for the enthusiast (lots of money, no jaw dropping performance increase)segment the i7 will rule them all. So the battle between blue and green will continue as is, for almost 3 years now AMD has lost the crown, another year isn't going to hurt them much. Things will get heated this time next year when more and more bulldozer and fusion rumors will start spreading.

    As of now, nothing new, in this review or the ones that will follow.
  • 6 Hide
    pauldh , June 1, 2009 11:19 AM
    radguySo did I miss somthing or where does it say what each of these processors is overclocked to. I get that the p2 x3 720be is at 3.67 but what about the rest of them.

    Thanks for pointing this out. No you didn't miss anything, the CPU-Z screenshots should have been put up in pairs CPU Tab / Memory Tab.

    Phenom II X4 940 BE - 3.793 GHz (18.5* 205) 1.5375V
    Phenom II X3 720 BE - 3.672 GHz (18.0* 204) 1.500V
    Phenom X4 9950 BE - 3.400 GHz (16.5*206) 1.425V
    Athlon 7750 BE - 3.383 GHz (16.5*205) 1.425V

  • 5 Hide
    buzznut , June 1, 2009 11:37 AM
    All I can say is Thank you. What a great article! I can't see anyone not considering the PhII X3 720 for a budget build.

    I'm glad to see my X4 940 is holding up so well. Prolly be another 2 months before I feel obsolete again!
  • 3 Hide
    buzznut , June 1, 2009 11:39 AM
    O, BTW isn't 1.5V extremely high for a PhII? I've never taken mine beyond 1.45V. I'm chicken
  • -4 Hide
    ct1615 , June 1, 2009 11:41 AM
    never understood why IDIOTS type in ALL caps EVERY other WORD.

    if you have a simple understanding of the english language and can type, the reader will know what words are emphasized.
  • -5 Hide
    ct1615 , June 1, 2009 11:42 AM
    DjEaZy... BIG THX to the Tom's crew... was not so hard after all? ... now, thx to YOU, we have a info about intel, nVidia and AMD/ATi solutions... how they stack up in price/performance/cost of ownership... NICELY DONE!!!


    never understood why IDIOTS type in ALL caps EVERY other WORD.

    if you have a simple understanding of the english language and can type, the reader will know what words are emphasized.
  • 0 Hide
    cinergy , June 1, 2009 12:02 PM
    These benchmarks are obsolete and shouldn't be compared to anything. Firstly cat 9.2 is from february, now its june and cat 9.5. AMD also has had 7850 and 955 processors available quite awhile for better performance.
  • 0 Hide
    programmed4gamin , June 1, 2009 12:04 PM
    radguySo did I miss somthing or where does it say what each of these processors is overclocked to. I get that the p2 x3 720be is at 3.67 but what about the rest of them. Am I missing it somewhere (very possible) or do I have to look back at your previous articles to figure it out? shouldn't that be on the test systems and configuration page. I am trying to sort through the data.


    Check out screens from CPU-Z. Good article.. i say: FINALLY!

    How about using AMD and Intel CPUs in GPU tests in the future? I'm not gonna buy Intel no matter what, so furter articles with AMD processors i would gladly welcome
  • 0 Hide
    ufo_warviper , June 1, 2009 12:21 PM
    That's odd, most of my previous post is no displaying... Maybe that's why it has a negative score? I noticed, I hunted for a post I submitted last last week on a different article and it looks like it never posted.
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