Overclocking

As cooling solutions do a better job of keeping the CPU at a lower temperature, it is reasonable to expect the overclocking capabilities of the CPU will increase. In each test of a cooler we measure the highest stable overclock of a standard X6800 processor under the following conditions:

CPU Multiplier: 14x (Stock 11x)
CPU voltage: 1.5875V
FSB Voltage: 1.30V
Memory Voltage: 2.00V
nForce SPP Voltage: 1.35V
nForce MCP Voltage: 1.7V
HT nForce SPP <-> MCP: Auto

Memory is set to Auto timings on the 680i and memory speed is linked to the FSB for the overclocking tests. This removes memory as any kind of impediment to the maximum stable overclock. Linked settings on the 680i are a 1066FSB to a memory speed of DDR2-800. As the FSB is raised the linked memory speed increases in proportion. The same processor is used in all cooling tests to ensure comparable results.

Highest Stable Overclock (MHz)

The Thermalright Ultima-90 reaches a stable 3.90 GHz, matching the top performers we have tested like the Tuniq 120, Thermalright Ultra-120, Scythe Infinity with push-pull fans, and the Scythe Ninja Plus B/OCZ Vindicator running a high output SilenX IXTREME fan. The only air cooler that outperforms the Ultima-90 in overclocking is its big brother - the Ulltra-120 eXtreme.

These results are with a high output 120mm fan. Results with a 92mm fan are slightly lower, with a top overclock of 3.87GHz. As seen in the scaling charts the 120mm and 92mm fan results are almost the same to the top of the speed charts. Cooling performance is also about the same with either a 120mm or 92mm driving. However, the 120mm fan allows a slightly higher overclock.

If wattage is considered, a stock X6800 consumes about 75 watts, where the 3.83GHz OC pulls about 150 watts - double the amount required at stock speed. At the voltage required for stability at 3.90 GHz with a 120mm fan, the CPU wattage is around 161W. The highest air result ever with this CPU at 3.94GHz translates into about 165W, where the 92mm top of 3.87GHz translates into around 158W. Considering the smaller size and reduced weight of the Ultima-90, this performance can only be considered outstanding.

Note that a C2D pushed to the incredible overclocks they can reach draws a lot of power, and our cooling test is designed to find where the top coolers fail. Keep this in mind when looking at our cooling results. Many of the middle coolers in our roundup have done very well when tested with AMD processors or with less demanding cooling test procedures.

Scaling of Cooling Performance Conclusion
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  • Wesley Fink - Monday, August 20, 2007 - link

    Corrected.
  • CZroe - Monday, August 20, 2007 - link

    "The Ultima-90 is also the first Thermalright we have tested with four sets of fan wire mounting holes. This means with the right fan wires you can mount two fans in a push pull configuration."
    So why not test it in this configuration? You had both fans, and one of your statements even seems to say this when taken out of context:
    "our test configuration needs to look at the Ultima-92 with both a 120mm fan and a 92mm fan."

    INDEED! The Ultra-120 Extreme could mount two fans with a second set of clips and rubber, so I always thought that it was a shame that they weren't included. Sure the clips were designed to use the same holes (they didn't have to be), but one could easily be forced into the second set of holes from the top and the other could be forced into the second set of holes from the bottom.

    Anyway, I noticed that there were no views of the underside or mention of the finish. I assume that it's identical to the Ultra-120 Extreme (which I am regretting buying after reading this ;)).

    Also, the comparison showing both 120 and 92mm fans mounted shows the rubber strips mounted incorrectly for the 92mm fan. Does the final retail version include two more of these for a push-pull config?

    Also, your cooler comparisons had me strongly considering a Cooler Master Hyper 6+, but it is 100% unavailable. I tried my darndest to buy one. Cooler Master does not offer it, so it only makes sense to remove it from the comparison. I know that it fills a unique position, but in light of availability, it really needs to go (especially seeing how crowded the chart is getting).
  • Wesley Fink - Monday, August 20, 2007 - link

    The Ultima-90 includes one set of rubber strips, one set of 120mm fan clips, and one set of 92mm fan clips. Since the height is different than the Ultra-120 series those fan clips will not work and extras for the Ultima-90.

    Therefore, we did not have the clips for testing push-pull with matched fans. We will try to test this when we do a retest of some of the top units.

    The finish is about the same as the Ultra-120 eXtreme, and Thermalright has written many buyers who questioned the curvature that the " . . . the convex surface is made that way to work well with the bolt down retention mechanism."
  • CZroe - Wednesday, August 22, 2007 - link

    I know that the clips on the Ultra-120 Extreme are different, so I wasn't suggesting/considering using clips from one on another (what a waste of an Ultra-120 Extreme ;)). Just testing the included clips with the two fans you've been using simultaneously would be enough.

    I certainly wasn't suggesting matched fans. I've been told that push/pull configurations only help with a lower CFM fan pushing and a higher CFM fan pulling or else you get no increased CFM or decreased noise. This was the consensus when I had to quiet down my Shuttle SN45G XPC (SFF) a few years ago with a fan duct and some case modding.

    Thanks for the info about the finish. Considering the top-end performance of the Ultra-120 Extreme, I don't think anyone will question their decision to do that (it certainly didn't impact performance!).
  • Egglick - Monday, August 20, 2007 - link

    This is an excellent article, along with what sounds to be an excellent heatsink. However, I must echo some of the same feelings that other posters have been expressing:

    Fix the test system's setup.

    If we want to get a legitimate idea of how loud a cooler is, you're going to have to do better than 38db @ 24in for a noise floor. Swap out the videocard for a fanless model, and if necessary switch to a quieter PSU. Hell, go with an 8500GT if you need to. We're not testing the framerate of the videocard, we're testing the noise/performance of CPU coolers.

    Let readers judge the heat/noise of videocards on their own merit.
  • yacoub - Monday, August 20, 2007 - link

    Totally agree!!
  • Tiamat - Monday, August 20, 2007 - link

    I know its tough to show all the data, but I was wondering if you could include insets that show just the heatsinks in the neighborhood of the performance of the reviewed specimen. When displaying all of the data at the same time with much of the graphs overlapping, its very difficult to find the appropriate plot. In fact, I gave up trying after 3 seconds (standard attention span when looking at graphs) -- this kind of renders the plots useless! Usually the take home message should be as quick in the plots as it is in the text, if not quicker!

    My suggestion would be to show only 5 trends in the graph (including the intel retail for reference, two above, two below) while keeping all of the data in the table for those who need the ancillary information.

    Thanks and I hope this helps!

    Keep up the good work!
  • Final Hamlet - Monday, August 20, 2007 - link

    I don't get the attraction of max overclocks... are they any good, except ego-pushing?
    What I would be really interested in is how these coolers do in a stock PC without any fans. That would be _really_ interesting... otherwise I don't see any point in buying these things or overclocking 10MHz higher (oh, great, you did it...).
  • coolerman - Monday, August 20, 2007 - link

    Most of the good air coolers seem pretty comparable. The 30-90 MHz overclocking differences are laughable, and while the temperature varies a bit most coolers fall into one of two categories: top out at ~3.9GHz and 37-45C, or top out at ~3.8GHz with slightly higher temperatures at the lower clock. The Ultima-90 is nice in that it weighs less, but the Tuniq 120 does manage to best it in several tests - i.e. with 92mm at top OCs - and technically costs less once you add in shipping and fans. Speaking of which, am I the only one that finds the $20 fan with a $50 HSF to be humorous? Fan makers must make a decent profit, compared to the poor heatsink blokes!

    Also, do you think you could possibly cram any more entries into the scaling charts? Perhaps sort them by some reasonable criteria while you're at it - say, temperature for instance? The upper portion is useless, as it's just a cluster of illegible lines, and the lower table is almost sorted alphabetically, which means if I'm looking for similar coolers I have to stare for a long time. And those lovely colours… the large images help some, but fundamentally there's just too much data there now I think.

    Anyway, seems like even though Thermalright got a glowing review, the iCEAGE, Hyper 6+, Vindicator (with SilenX), Ninja (with SilenX), and Tuniq 120 are all in the same ballpark. Of course, some of those are tough to find (iCEAGE anyone, or Tuniq across the pond?), but for the price the Ultima-90 really doesn't look that special. Fan + shipping means you'll pay probably $65-$70, which while better than the $85 you'd pay for Ultra-120 eXtreme is still not exactly a steal. Ninja is $45 shipped, Tuniq is about $55 shipped. $55-$60 shipped, plus a fan? You'll have to do better than that! As it is, I'll buy whatever is cheapest within reason - which is often Scythe, for the money. (Let's not even talk UK/European prices on most of this stuff, as I'm sure the majority of you don't care.... I'll just avert my lustful eyes from Newegg.com, Xoxide, etc.)

    Now, my real question is how a true water cooling setup compares to all of these coolers. Fundamentally, air and water cooling are still limited to room temperature. Water simply cycles all the liquid around to a potentially larger radiator (and reservoir). I'm sceptical that most water cooling solutions will really do much better than something like the Ultra-120 eXtreme, but I'd like to see some results using your own testbed. If you ever do water, though, please run it at full load for 8 hours or so. Some water setups depend on the water starting at a low temperature, and as it heats up they can't maintain cooling efficiency. I had one that would crash after about two hours of intense gaming every time unless I turned the overclocks down.

    Last but certainly not least, the "we're thinking about a new cooling test system so that our noise testing might actually have merit" talk is getting a wee bit old. It's about time to actually move on I'd say. I'd like a more moderate (fanless!) GPU in there in terms of noise, if only to allow us to see how quiet (or not) the coolers really are. Your PSU testing seems to have a bit better equipment for noise analysis, so maybe you can get some help with that area. I don't think X38 is necessary, just like 680i isn't necessary for the most part, but I suppose getting more or less useful temperature readings might be needed. Just toss everything that doesn't make the top 5 and move to the new testbed! (Easy for me to say, since I'm not doing all the work!)

    Cheers,
    Charles
  • Wesley Fink - Monday, August 20, 2007 - link

    While the frequency difference may appear minor at the top, the wattage dissipation is not. For the last two reviews I have also been quoting wattage in the review commentary for comparison.

    A stock X6800 represents 75 watts, while that CPU at 3.83Ghz is at 150W - or double the heat to dissipate. At 3.90Ghz at the voltages required the requirement is 160 to 161W, while at the Thermalright Ultra-120 eXtreme maximum stable speed of 3.94 GHz the wattage is around 166W.

    Many tests only consider air cooling results to 150W, but most readers buy secondary cooling to extend their overclock. Since the C2D overclock extremely well the wattages at some of the very high overclocks are very demanding.

    We have a water-cooling review in process for comparison with these results. Once that is done we will choose a few top performers for retest and start testing with the new cooling test bed. The new test bed will require retesting of all coolers included so that is why the shift when a section like top air-coolers is completed.

    Thr 92mm fan costs just over $6, while the 120 was $20. We used the Scythe S-Flex again because that was the fan used in testing the Thermalright Ultra-120 and the Ultra-120 eXtreme. We wanted to keep as many variables the same as possible.

    Looking at output and noise you should be able to select a value 120mm fan below $10 that meets your specs. The Yate Loon medium output fan, for example, is very popular as a value case fan. The Yate Loon D12SM-12 cost $6.99 retail and has specified output of 70.5cfm at 33db at 1650rpm.

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