Overclocking Intel’s Xeon E5620: Quad-Core 32 nm At 4+ GHz

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Conclusion

I can only lament the fact that Intel isn’t selling the Xeon E5620 on the desktop as a different K-series SKU with an unlocked multiplier. I’d even take a $10 or $20 premium on a part like that. Nevertheless, with a bit of fancy footwork, it’s possible to overclock this thing to 4 GHz and beyond.

Is Intel’s Xeon E5620 a solid enough value to displace CPUs like the Core i7-930 and -950 in the minds of ambitious overclockers? Not definitively, no. It’s on par. But because its multiplier is set so low, you really need 1) a good motherboard and 2) a solid approach to overcoming BCLK frequency limitations.

Fortunately, Asus’ Rampage III Formula is good enough. And with relatively little effort, 4 GHz is a piece of cake. It takes a little more ambition to get 4.2 or 4.3 GHz running stable. But even still, the 32 nm chip doesn’t run hot at all—I never saw the thing crest 80 degrees, even with 1.425 V applied to it. A combination of higher IOH voltage, an elevated PCIe clock, and lower QPI data rates are all viable strategies for breaking past that pesky BCLK wall so many enthusiasts run into.

Don’t expect boatloads of additional performance due to the extra 4 MB of L3 cache—in our testing, there were only a couple of instances where the overclocked Westmere-EP-based Xeon E5620 outperformed the Bloomfield-based Core i7 at 4 GHz (and that was with dissimilar memory clocks, so a couple of variables likely came into play).

What you can expect, though, is a processor that requires less voltage at 4 GHz and beyond than those based on the 45 nm process. Consequently, it runs less hot and consumes less power. For my money, I’d be far more comfortable with it in my own workstation, long-term, than a CPU running at 90+ degrees under load. For many overclockers, those attributes alone won’t be worth the $100 price premium Intel’s Xeon E5620 holds over its Core i7-930. For others, that $100 is far more palatable than an extra $600+ for the Core i7-970—the only enthusiast-class 32 nm CPU in the company’s desktop lineup.

With Sandy Bridge still months away, aimed at the mainstream, and largely inaccessible to the overclocking community (save a couple of K-series SKUs that’ll be marked up), the Xeon E5620 may very well be a viable choice for power users who just can’t wait for Intel to refresh its enthusiast platform late next year with LGA 2011.

Chris Angelini
Chris Angelini
Chris Angelini is an Editor Emeritus at Tom's Hardware US. He edits hardware reviews and covers high-profile CPU and GPU launches.
56 Comments Comment from the forums
  • intelx
    i wish it had higher multiplier it would of been a great processor to recommend than paying $10000 for the i7 970.
    Reply
  • JOSHSKORN
    I wonder if it's possible and also if it'd be useful to do a test of various server configurations for game hosting. Say for instance we want to build a game server and don't know what parts are necessary for the amount of players we want to support without investing too much into specifications we don't necessarily need. Like say I hosted a 64-player server of Battlefield or CoD or however the max amount of players are. Would a Core i7 be necessary or would a Dual-Core do the job with the same overall player experience? Would also want to consider other variables: memory, GPU. I realize results would also vary depending on the server location, its speed, and the player's location and speed, too, along with their system's specs.
    Reply
  • cangelini
    JOSHSKORNI wonder if it's possible and also if it'd be useful to do a test of various server configurations for game hosting. Say for instance we want to build a game server and don't know what parts are necessary for the amount of players we want to support without investing too much into specifications we don't necessarily need. Like say I hosted a 64-player server of Battlefield or CoD or however the max amount of players are. Would a Core i7 be necessary or would a Dual-Core do the job with the same overall player experience? Would also want to consider other variables: memory, GPU. I realize results would also vary depending on the server location, its speed, and the player's location and speed, too, along with their system's specs.
    Josh, if you have any ideas on testing, I'm all ears! We're currently working with Intel on server/workstation coverage (AMD has thus far been fairly unreceptive to seeing its Opteron processors tested).

    Regards,
    Chris
    Reply
  • You could setup a small network with very fast LAN speeds (10Gbps maybe?). You can test ping and responsiveness on the clients, and check CPU/memory usage on the server. Eliminating the bottleneck of the connection and testing many different games with dedicated servers one can actually get a good idea of what is needed to eliminate bottlenecks produced by the hardware itself.
    Reply
  • Moshu78
    Dear Chris,

    thank you for the review but your benchmarks prove that you were GPU-bottlenecked almost all time.
    Letme explain: i.e. Metro 2033 or Just Cause 2... the Xenon running at 2.4 GHz provided the same FPS as when it ran at 4 GHz. That means your GPU is the bottleneck since the increase in CPU speed therefore the increase in the number of frames sent to the GPU for processing each second does not produce any visible output increase... so the GPU has too much to process already.
    I also want to point out that enabling the AA and AF in CPU tests puts additional stress on the GPU therefore bottlenecking the system even more. It should be forbidden to do so... since your goal is to thest the CPU not the GPU.

    Please try (and not only you, there is more than 1 article at Tom's) so try to reconsider the testing methodology, what bottleneck means and how can you detect it and so on...

    Since the 480 bottlenecked most of the gaming results are useless except for seeing how many FPS does a GF480 provide in games, resolutions and with AA/AF. But that wasn't the point of the article.

    LE: missed the text under the graphs... seems you are aware of the issue. :) Still would like to see the CPU tests performed on more GPU muscle or on lower resolutions/older games. This way you'll be able to get to the real interesting part: where/when does the CPU bottleneck?
    Reply
  • Looks to me to be a pointless exercise. I have been running an i7-860 @ 4.05 Ghz and low temps for more than a year now so why pay for a motherboard that expensive plus the chip?
    Reply
  • Cryio
    I have a question. Maybe two. First: Since when Just Cause 2 is a DX11 game? I knew it was only DX10/10.1 . And even if it is , what are the differences between the DX10 and 11 versions?
    Reply
  • blibba
    Note: Higher clocked Xeons are available.
    Reply
  • omoronovo
    blibbaNote: Higher clocked Xeons are available.
    However, I'm sure everyone is aware of how sharply the price of Xeons rise above the lowest-of-the-low. I expect a Xeon capable of 4.5ghz (a good speed to aim for with a 32nm chip and good cooling), you would already be over the costs of purchasing a 970/980x/990x, especially considering how good a motherboard you would need to get - a Rampage III extreme is possibly one of the most expensive X58 boards on the market, offsetting most of the gains you'd get over a 45nm chip and a more wallet friendly board - such as the Gigabyte GA-X58A-UD3R.
    Reply
  • compton
    This is one of the best articles in some time. I went AMD with the advent of the Phenom IIs despite never owning or using them previously, and I didn't once long going back to Intel for my processor needs. But I think that may have changed with the excellent 32nm products. The 980X might be the cat's pajamas, but $1000 is too much unless you KNOW you need it (like 3x SLI 480s, or actual serious multithreaded workloads when TIME = $$$). The lowly i3 has seriously impressed the hell out of me for value/performance, heat, and price/performance. Now, this Xeon rears it's head. While still pricey in absolute terms, it is still a great value play. Intel has earned my business back with their SSDs -- now might be the time to get back in on their processors, even if Intel's content to keep this chip in the Xeon line. Thanks for the illumination.
    Reply