Cooling at Stock Speed

Some users will never overclock their CPU, but they still want to run the coolest CPU temperatures possible to enhance stability and extend CPU life. All temperature benchmarks were compiled with CoreTest, a public domain utility that is quite stable with reproducible results on the Intel platform. This required retesting a cross-section of the best coolers evaluated so far at AnandTech. To better document performance in the large speed gap between 2.93GHz and 3.73GHz, the intermediate value of 3.33GHz was added to all test results and results were compiled at 3.33GHz during the retest of the coolers.

X6800 Stock (2933MHz) IDLE Temperature

The very good Intel stock air cooler keeps the X6800 at 31C at idle, compared to the top Thermalright Ultra-120 eXtreme at 24C, Corsair water at 24C, and Swiftech water at 27C. By comparison the OCZ Vendetta manages a decent 27C, while the Scythe Kama Cross was very close to the stock fan at 30C. This was with a 120mm fan on the Kama Cross as results with the 100mm fan were exactly the same as Intel retail at 31C.

The Vendetta results were what would be expected of a decent mid-priced cooler, and they were just 2C higher than the more expensive but also small Thermalright Ultima-90 running a 120mm fan. The Scythe results were a bit disappointing considering it is larger and more expensive than the Vendetta.

All these results except the Scythe are significant improvements over the Intel stock cooler performance at 31C. In comparing results please keep in mind the test results from the new cooling bed using CoreTemp are not directly comparable to earlier cooling results.

It is more difficult to effectively simulate a computer being stressed by all of the conditions it might be exposed to in different operating environments. For most home users CPU power is most taxed with contemporary gaming. Therefore our stress test simulates running a demanding contemporary game.

The Far Cry River demo is looped for 30 minutes and the CPU temperature is captured at 4 second intervals with the NVIDIA Monitor "logging" option. The highest temperature during the load test is then reported. Momentary spikes are ignored, as we report a sustained high-level temp that you would expect to find in this recording configuration. This test configuration roughly equates to an 80% CPU load test using Intel TAT. Cooling efficiency of the Scythe and OCZ coolers was then compared under load conditions at stock speed to the retail HSF and other recently retested CPU coolers.

X6800 Stock (2933MHz) LOAD Temperature

The Idle pattern of the OCZ and Scythe Kama Cross was repeated in load testing. The Kama Cross was very close to Intel retail cooling results to 3.73GHz, but it did manage to continue on to 3.83GHz with the 120mm Scythe S-FLEX fan. The stock 100mm fan topped out at 3.80GHz. This translates into 48C at 2.93GHz load to 64C load at 3.73GHz. The top Thermalright eXtreme does much better at 36C at 2.93, 49C at 3.73 and 59C at 3.94GHz . The entry level water coolers performed close to the levels of the Ultra-120 eXtreme.

The OCZ Vendetta fared much better, reaching performance expected of a quality midrange air cooler. As you can see in the chart, performance fell in the middle between stock Intel and the top air and entry water coolers. The Vendetta overclock reached a 3.87GHz overclock, which matched the Thermalright Ultima-90 running a similar 92mm fan. The Ultima-90 performed best with a 120mm fan.

New CPU Cooling Test Configuration Noise
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  • Wesley Fink - Monday, October 1, 2007 - link

    There is only one game available that may possibly perform better with a quad CPU. Our original thinking was that we would wait to move to quad testing until games are launched that give us a reason to buy a quad-core - somewhere in the future.

    However, the point is well-taken that quads do generate more heat than dual-core processors, so we will be doing a comparison in the next few weeks on a range of coolers tested on a quad-core CPU.
  • Acanthus - Monday, October 1, 2007 - link

    That is fantastic, not all of us buy quads for gaming :D

    I have one for encoding.
  • strikeback03 - Tuesday, October 2, 2007 - link

    same here, though it would be nice if Premiere would make use of more than one core.
  • Spacecomber - Monday, October 1, 2007 - link

    The graphs and the discussion of them seemed out of synch, especially on page 5. It's as if the chart being discussed didn't get included or the discussion is meant for another section.

    Anyway, I got confused at that point, just looked at the graphs, and drew my own conclusions from there on. ;-)
  • Wesley Fink - Monday, October 1, 2007 - link

    The Intel Retail results on p.5 had not been updated for CoreTemp results. That has now been updated. Hopefully the commentary now matches the graphs.
  • Spacecomber - Monday, October 1, 2007 - link

    Yup, the previous bar for the intel heatsink said something like 41 deg, which left me scratching my head.

    The discussion of how the cooling scaled with higher clock speeds also seemed out of place on that page, since there is no graphical representation of that until you get to page 7. Perhaps you were just making those comments paranthetically on page 5, but I wasn't clear why it was being discussed where all the results being graphically presented were for default clock speeds.
  • FrankThoughts - Monday, October 1, 2007 - link

    ...that took one look at the Scythe "I'm an X! Isn't that AWESOME!" design and immediately figured performance was going to suck? Repeat after me: gimmicky cooler designs do NOT work well! Just look at the first image of the cooler: all the closely packed fins, lots of gap between the fan and the fins, and you can already guess that most of the air so going to go around the fins rather than through them.

    Maybe a plastic shroud around the HSF would have helped, but even then a large amount of air would just go through the center gap. This is one of those designs that looks nifty but has some bassackwards thermodynamic "theory" at its core.
  • strikeback03 - Tuesday, October 2, 2007 - link

    I'm just surprised they let something out that sucks this bad. If the performance were at least a little better than stock some might buy it for the looks, but this performance is just embarrassing to Scythe.
  • puffpio - Monday, October 1, 2007 - link

    I agree
    You can immediately look at it and see that the air the fan blows is going to go AROUND the heat sink...basic fluid dynamics..path of least resistance

    But also w/ the OCZ cooler, they cut out some heat sink fins to make a curve shape...so you loose thermal capacity and gain aesthetics?

    Someone needs to design an enthusiast heat sink and fan that consulted a thermal and aerodynamic engineer...perhaps tapping into the skill set of people who design car radiators..
  • KazenoKoe - Wednesday, October 3, 2007 - link

    I would like to know how the Scythe cooler performs with 2 smaller fans, one for each heatsink, instead of one fan at an odd angle.

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