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Overclocking: Core i7 Vs. Phenom II

AMD’s Phenom II Platform, Configured, And Priced

What We Recommend

AMD Platform
MotherboardAsus M3A78-T
ProcessorPhenom II X4 940
CoolerAjigo MF091
MemoryCorsair XMS2 4 GB (2 x 2 GB) DDR2-1066
GraphicsAMD Radeon HD 4870 X2
StorageSamsung Spinpoint F1 1TB 7,200 RPM
PowerPC Power and Cooling 750 W
OpticalLite-On DH-4O1S

AMD’s Dragon platform, though new in name, is the 790GX, which has been around for a while already. Thus, it was much easier to get all of the components for this one.

At the time of writing, the pieces for this platform add up to about $1,300—$250 less than the Intel-based configuration. The savings is substantial and will definitely have to figure into our conclusion. After all, you could get a Blu-ray burner in the AMD box with the difference, upgrade the processor’s cooling, or simply pocket the extra cash.

Familiar territory--Phenom II drops right into the AM2+ interface

Overclocking Phenom II

In contrast to the known overclocking potential of Core i7, Phenom II is still uncharted territory. Sure, it drops into the same AM2+ socket interface as its predecessor, but it centers on a new manufacturing node and, according to AMD, incorporates all of the goodness previously enabled by the Overdrive application and ACC automatically. Those enhancements are baked into the hardware, AMD says. As a result, we’ve seen some fairly impressive results with the Phenom II on liquid nitrogen. But that hardly helps enthusiasts interested in one of these platforms at home.

AMD already seems to have a fairly good idea what a Phenom II X4 940 will do with air cooling. Somewhere between 3.6 and 3.9 GHz should be doable, according to talks we’ve had with folks in the company’s lab. We set our sights high and gunned for 3.9 GHz right out of the gate.

Overclocking with a Black Edition Phenom II is as easy as it was using previous Phenom chips—an unlocked multiplier remains the most straightforward way to scale up and down 100 MHz at a time on a 200 MHz reference clock. With 19.5x keyed in, we set the processor’s voltage to 1.55 V, which was the maximum AMD recommended for air cooling.

Blue screen loading up into Windows. That's a no-go.

Dropping down to 3.8 GHz with a 19x multiplier allowed us to boot into Windows, but starting any of our benchmarks resulted in a quick crash. We then tried 18.5x, yielding 3.7 GHz. At that speed (and after increasing the processor voltage to 1.625 V—which was far higher than we’d leave the system running), we were able to complete most synthetic and gaming benchmarks. But Call of Duty and the productivity-oriented tests just wouldn’t stabilize. We settled for 3.64 GHz by dropping the multiplier to 18 and adding 2 MHz to the reference clock (allowing us to also drop the voltage down to 1.6 V). That’s a better overclock than we ever saw with the 65 nm Phenoms, but not quite what we were hoping for with Phenom II.

Mis-match--our BIOS setting agree with CPU-Z, which disagrees with Overdrive.

The good news was that, even at 1.625 V, heat never seemed to be an issue, as Overdrive reported temperatures below 60 degrees Celsius throughout our suite. Then again, even the latest version of the software, as recommended for use by AMD, mis-reported our platform’s processor and memory clock speeds. Fortunately, we’re still more comfortable with BIOS overclocking anyway.

  • 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?
    Reply
  • 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.
    Reply
  • 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).
    Reply
  • 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.
    Reply
  • 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.
    Reply
  • 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.
    Reply
  • 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?
    Reply
  • jtnstnt
    Please explain.
    Reply
  • 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
    Reply
  • jtnstnt
    I was wondering because i didn't see an explanation in the article.
    Reply