Overclocking: Core i7 Vs. Phenom II

Conclusion

As far as we can see it, there are four different factors that go into the purchasing decision of one of these next-gen platforms.

The first is price. AMD has the upper hand here. Although its Phenom II X4 940 is priced fairly close to Intel’s Core i7 920, 790GX-based motherboards cost in the neighborhood of $150, while high-end X58 platforms generally tend toward $300 (although we’ve recommended a $250 model here). DDR3 memory is still significantly more expensive than DDR2. Populating three channels, the more modern technology is going to bear a notable premium over two channels of the more mainstream type. In all, the Phenom II machine costs about $250 less to build than our i7 box did, while arming the AMD platform with a better aftermarket cooler would have shaved $50 or so from its advantage.

Next is performance. Intel maintains its advantage in this one, even with both configurations overclocked. We very effortlessly achieved a 3.8 GHz overclock on the i7 920 by bumping its Bclk up to 190 MHz and keeping all other settings in place. Knowing that our own German lab was able to reach 3.8 GHz stably on air (and AMD’s lab team said to expect frequencies up to 3.9 GHz at 1.55 V), we pushed our X4 940 extremely hard. While we were able to boot at up to 3.8 GHz, benchmarks wouldn’t finish consistently until we had dropped down to 3.64 GHz—and that was still at 1.6 V. Anything less and even that speed wasn’t 100% solid. Given the speeds we were able to achieve, Intel’s entry-level Core i7 walked away from AMD’s fastest Phenom II in every single one of our tests.

Third, you have power. We’re giving this one to AMD, as well. At idle—where you’ll spend most of your time—the overclocked Phenom II spins down to 800 MHz and yields some impressive power figures. Once it shoots back up to 3.64 GHz, it’s sucking down more juice than Intel’s 3.8 GHz Core i7. However, we anticipate that most enthusiasts aren’t going to peg their chips at redline very often.

Finally, there’s the upgrade question. For owners of existing Socket AM2+ motherboards, today’s Phenom II is a drop-in component. Provided that your board and graphics are beefy enough to warrant the new CPU, stepping up is a matter of spending $275. Conversely, adopting i7 means buying a CPU, motherboard, and DDR3 memory, at least. This isn’t necessarily a bad thing. Intel has always been aggressive about nudging the bleeding edge forward and advocating new technologies—sometimes to its own detriment. We know DDR3 is going to replace DDR2, and it’s nice to have an X58 board able to support CrossFireX and SLI. AMD’s upgrade path simply lets enthusiasts stretch their aging hardware out a little bit longer.

 So What Do I Buy?

The Core i7 and Phenom II seem suited to two different customers. Indeed, there will undoubtedly be gamers who go all-AMD and are willing to sacrifice a bit of speed in order to save money and Intel loyalists who adopt i7 at a bit of extra cost for its newer technology. We thus see distinct advantages to each platform.

For the gamer or multimedia aficionado with a mind to performance, Intel’s Core i7 920 overclocked to 3.8 GHz simply delivers the most compelling experience. The ~$250 hardware price premium is the cost of entry over AMD’s solution, and we think it’s worth paying. AMD is planning its own shift to DDR3 in the first half of 2009, and less-expensive X58 boards are trickling out (the cheapest right now being Gigabyte's $210 EX58-UD3R), so the cost-difference will continue getting smaller.

If you’re instead buying for a more productivity-oriented purpose, the Phenom II makes sense. After all, it’s able to handle every task nearly as well as i7 does (both platforms overclocked, of course), it drops into existing AM2+ motherboards, it costs less, and in a majority of situations, will use substantially less power—even highly-tuned, as we've done here. We didn’t have as much luck overclocking the Phenom II as we expected, but the chip is still a notable improvement over AMD’s 65 nm Phenom series.

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221 comments
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    Top Comments
  • bernardv
    This Phenom II overclock is very very far from optimal. Here are some points:
    1. 790FX board should be used, FX is the top end chipset.
    2. Ph2 doesn't support ACC, check the forums where skilled people got this CPU beyond 4GHz on air, they know what they were doing.
    3. If you're doing bench you should try to get an optimal RAM speed as well. Your RAM was running 30% below stock 1066!!! You must raise core do better.
    17
  • cangelini
    Uncle,
    With the Black Edition, that's really the value there. You want to use the multiplier for a clean, easy overclock. Once you've found your ceiling, use the reference clock to fine-tune the setup.
    14
  • jtnstnt
    I'm curious about the heatsink selection on the Phenom II. I looked up the Ajigo MF091 and it didn't look too impressive. While the Intel system gets the Thermalright 120mm True extreme. Whats up with that?
    13
  • Other Comments
  • Roffey123
    At last a P2/i7 comparison to shut the people whining for one up. In all I think its a fair comparison - although I am disappointed that AMD's OC potential wasn't as good as they made it out to be. But as all overclockers know - not all chips are the same or have the same OC potential.

    The 3DS Max benchmark was puzzling as well, considering that i7 has 8 threads at its disposal. Do you guys have any idea as to why the AMD beat the i7 in that test; despite having only half as many threads?
    0
  • unclefester
    I thought it funny they use an ATI card on the Intel board (not that it makes a difference).
    Would have liked to see what the PII can gain or not gain by using the FSB not just the multiplier.
    Didn't see anything about memory timings either. As most PII OC's have been done at @880MHz.
    Overall a decent review.
    So Ford vs Chevy goes on.
    0
  • apache_lives
    I would love to see a high end overclocked Core 2 Quad 9 series in the tests here to see a price comparison - cheaper and already established platform etc.

    Also note that i7 platform should also feel more alive and responsive (un-benchmarkable) thanks to high memory bandwidths and more threads to balance things out like the P4C's and CL2 Dual Channel DDR1 - reguardless if it performed lower then the AMD A64's at the time it felt more responsive!

    Intel also has that more solid platform to back that CPU and options for Crossfire AND SLi so its more the premium option, but that cheaper AMD setup is too close to the i7 for my liking - a few shifts in prices and models should show an interesting result in the new few weeks.

    AM3 should be interesting, higher headroom + lower power etc (like 939 to AM2).
    -1
  • cangelini
    Uncle,
    With the Black Edition, that's really the value there. You want to use the multiplier for a clean, easy overclock. Once you've found your ceiling, use the reference clock to fine-tune the setup.
    14
  • vekere
    I hear AMD is going to hire Sylar to look at the new Core i7 processor so this year we will have an answer.
    -4
  • kschoche
    The WINRAR tests are so close to exactly half the time on the Intel chip compared to the AMD chip that I'd love to see how the results show up if you turn off hyperthreading, not that its a particularly meaningful result, but would be cool to look at still.
    1
  • jtnstnt
    I'm curious about the heatsink selection on the Phenom II. I looked up the Ajigo MF091 and it didn't look too impressive. While the Intel system gets the Thermalright 120mm True extreme. Whats up with that?
    13
  • jtnstnt
    Please explain.
    -5
  • apache_lives
    jtnstntI'm curious about the heatsink selection on the Phenom II. I looked up the Ajigo MF091 and it didn't look too impressive. While the Intel system gets the Thermalright 120mm True extreme. Whats up with that?


    Heh very good point there, although it depends on wether the limits of the OC was architectural or thermal
    6
  • jtnstnt
    I was wondering because i didn't see an explanation in the article.
    0
  • cangelini
    jtnstntI'm curious about the heatsink selection on the Phenom II. I looked up the Ajigo MF091 and it didn't look too impressive. While the Intel system gets the Thermalright 120mm True extreme. Whats up with that?


    The Ajigo sports a copper base, four heat pipes, and an aluminum fin array. You're right--it's not a particularly spectacular heatsink, though it was the best Phenom II-compatible cooler in the lab. As a result, I made it a point to mention that stepping up to a better cooler might have yielded better overclocking, but would also erode some of AMD's price advantage as well.

    Heatsink aside, after talking to a number of colleagues from other sites at this year's CES, it sounds like the overclocks here are indeed representative of what others were able to do, even using different heatsinks. I'll look into getting more in the way of air cooling and hope for better results.
    3
  • bernardv
    This Phenom II overclock is very very far from optimal. Here are some points:
    1. 790FX board should be used, FX is the top end chipset.
    2. Ph2 doesn't support ACC, check the forums where skilled people got this CPU beyond 4GHz on air, they know what they were doing.
    3. If you're doing bench you should try to get an optimal RAM speed as well. Your RAM was running 30% below stock 1066!!! You must raise core do better.
    17
  • arkadi
    jtnstntI'm curious about the heatsink selection on the Phenom II. I looked up the Ajigo MF091 and it didn't look too impressive. While the Intel system gets the Thermalright 120mm True extreme. Whats up with that?

    P2 did go more than 60c, that what the article said any way. So i don't think it meter
    -1
  • falchard
    I think you got the wrong end of the silicon with the chip. Anandtech was able to reach a stable 3.9 GHz with 1.52 volts.
    0
  • cangelini
    bernardv

    Bernard, 790GX is actually a newer platform than 790FX, and the only way stepping *back* to that one could have made a difference would have been if we were testing multiple graphics cards, in which case the chipset's PCI Express connectivity would have benefited it.

    Re: ACC--not sure if you were aware, but the enhancements rolled into ACC that made the Phenom a better overclocker are *already* rolled into Phenom II. Therefore, it doesn't need to support ACC since those capabilities are in-hardware.

    Re: RAM speed, we're using DDR2-1066. Per this page, that is the maximum official supported spec for the AM2+ version of the chip. Not sure if you mis-read that we were using DDR2-800, perhaps.

    All the best!
    6
  • cangelini
    falchardI think you got the wrong end of the silicon with the chip. Anandtech was able to reach a stable 3.9 GHz with 1.52 volts.


    And our own German lab was able to run 3.8 GHz at 1.55V and even boot at 4 GHz. And there's the variability of overclocking for ya. Everyone's experience is going to be different, and I can assure you that an extra 100-200 MHz would not change the tide of this comparison.
    6
  • eodeo
    Could you please disclose what are you testing in Max 9, maybe even share the scene so we could also test it? By your own scoring, i920 @ 3.8ghz in this test is slower than c2q 6600 @ 2.4ghz. I know something whent wrong, but I dont know what.
    2
  • cangelini
    eodeoCould you please disclose what are you testing in Max 9, maybe even share the scene so we could also test it? By your own scoring, i920 @ 3.8ghz in this test is slower than c2q 6600 @ 2.4ghz. I know something whent wrong, but I dont know what.


    Sure! From the Test Setup page (page 4) of this story:
    Version: 9.0, Rendering Dragon Image at 1920x1080 (HDTV)

    In essence, this is a single image being rendered out at 1920x1080. If you email me, I'd be happy to send along the source data (cangelini at bestofmedia dot com).
    2
  • nashville
    hey, in your ph2 review, power consumption on i7 was measured from 12v rail. i read uncore/cache dont get power from 12v rail, is this correct. if it is, will affect your measurements?
    0
  • eodeo
    Thanks for the quick response Chris! Will do.
    0