Overclocking

In the review of the Thermalright Ultra 120, which matched the 3.90GHz highest overclock of the best tested coolers, we concluded that the maximum stable overclock of this X6800 processor on air was likely 3.90GHz. This looked reasonable considering the dual-fan Scythe Infinity, the Tuniq Tower 120, and the Thermalright Ultra 120 all topped out at 3.90GHz. Other heatpipe towers all topped out below this threshold, with the better coolers very close to the 3.90GHz plateau.

We were wrong. Better air cooling was possible and we are seeing what that cooling can do for overclocking in the performance of the Ultra 120 Extreme. It is all about cooling, and as cooling solutions do a better job of keeping the CPU at a lower temperature, then 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: 1.90V
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 DDR2 memory speed of DDR2-800. As 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 Ultra 120 Extreme with the Scythe S-Flex fan set a new overclocking record by maintaining a stable 3.94GHz. This is the highest stable overclock we have reached with air cooling with this CPU. We could boot at speeds as high as 4.0GHz, but gaming performance was not stable at speeds higher than 3.94GHz. Increasing the CPU voltage also did not increase stability above 3.94GHz, as 1.60V was the maximum voltage usable without generating random reboots of the system.

The best coolers prior to the Ultra 120 Extreme have topped out at 3.90GHz. The 3.94GHz with the Ultra Extreme was something of a surprise, but it proves again that if you move enough air and use enough heatpipes in a good design you can further improve air cooling. Eventually the limit will be reached with air cooling, since it is not an active cooling solution. Air cooling cannot cool lower than the ambient temperature of the room, and it will therefore be outperformed by some active cooling solution like TEC or phase-change cooling. Water cooling is also limited by ambient temperature, but liquid is a better medium for absorbing and releasing the heat produced in CPU cooling. This is also part of the principal used in the design of heatpipes that are proving effective in the current crop of heatpipe towers.

At a 3.94GHz maximum overclock the Thermalright Ultra 120 Extreme is the best air cooler we have tested at AnandTech. It is clear Thermalright knew what they were doing in modifying the Ultra 120 design with additional heatpipes.

Scaling of Cooling Performance Final Words
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  • Clem - Thursday, March 15, 2007 - link

    Is the 'Intel Stock HSF for X6800' connected to a:
    1. Molex 12v outlet (3 pins utilized) fan running at full speed and would you know approximated what that speed that is ?
    2. 3 pin Motherboard header - fan running at full speed (approximately what RPM) ?
    3. 4 pin Motherboard header - fan running at various speeds ?

    I think the 'Intel Stock HSF for X6800' fan can run from 800 RPM to 2600 RPM but somethimes a motherboard will only let it run at 1600 RPM on the 4 pin header.
  • hox - Thursday, March 8, 2007 - link

    Here are my thoughts of the Anadntech Heatsink reviews, while helpful, there is a growing body of end user discrepancies in temperatures realized. This post is to stimulate discussion to determine why end users are not acheiving the same results (degrees C at idle and load) as reported in so many heat sink reviews.

    I would like to know what you have enabled or disabled in the bios that controls CPU automatic throttling. Typically that would include Enhanced C1 control (C1E), SpeedStep, and for my Asus MB, something called CPU internal thermal control.

    These settings affect how the cpu "handles" load and will affect the temps reported to the Ntune program. Programs like CpuZ and Coretemp and Ntune do not detect some of these rapid throttling instances, but the temps of the processor are reduced because of this throttling. The Righmtark CPU temp utility is one of the few programs I know that allows you to visualize this throttling even when you have several of the throttling paramters disabled.

    This issue is important because the temps you are seeing, even at idle, are very different for several of your reviewed heatsinks then what end users will experience when they have altered these parameters in the bios.

    I believe this will be helpful for end users to feel like the products your reviews are deeming as superior are performing in their hands in a manner similar to your review. Please provide the bios settings to help the end users decide if the equipment they have purchased is functioning properly.

    I suspect by doing this, many RMAs and emails to the manufacturer would be reduced.

    There is a clear 10C difference between the reported CPU temps at both idle and full load for my QX6700 cpu caused by changing these three settings. Enabling these parameters in the bios I routinely see temps of 33 to 35 C for the cores of my QX6700 at stock speeds, MB temp is 35C. Disabling these parameters, temps on all 4 cores rise to 44C. Thus discrepancy in temps could lead someone to think that the Monsoon II lite cooler I am using is malfunctioning, when in reality it is working properly.

    Also it would be helpful if you also tested these devices with the quad core processors which have a higher heat output. By testing the quad core cpus the high end capacity of these heat sinks to move heat would be tested. Providing the thermal resistance Degrees C/Watt would also be a helpful guideling for these devices.

    It would also be helpful to comment whether the side door will fit with the thermalright heat sinks. As far as I know this heat sink is taller than the Tuniq which caused end users to move side panel fans and vents.

    Thank you
  • Wesley Fink - Sunday, March 11, 2007 - link

    All BIOS settings that affect automatic throttling are turned OFF in our reviews.
  • classy - Thursday, March 8, 2007 - link

    But unless you test all of the top solutions with the same fan, there really is no way to determine if one is truly better than the other. While I understand the logic for testing them as is, to not explore apples to apples is clearly short sighted. Now we know that the Extreme 120 is better than the Ultra because they were both tested with same fan. Great job though none the less. Very good quality on these heatsink reviews.
  • chyew - Wednesday, March 7, 2007 - link

    I'm quite surprised that the Scythe Ninja is omitted. Wesley, can you be kind enough to add in Scythe Ninja? Thanks!!!!
  • Gary Key - Thursday, March 8, 2007 - link

    Wes will have the Ninja B review up after he returns from vacation. It appears in early testing to be a very good solution also.
  • quanta - Wednesday, March 7, 2007 - link

    That's just great, the a.s.S-Flex sounds like another potential source where rookit will strike... :)
  • lopri - Wednesday, March 7, 2007 - link

    I might have missed this information so if that's the case please someone enlighten me how heavy this HSF is? Considering the heatpipes are made of copper outfit and whatever liquid-ish stuff Thermalright chose to use, the added weight from 2 extra heatpipes wouldn't be trivial, is my guess. The Ultra 120 is already quite heavy and I'd like to know this Extreme version is safe enough for average ATX motherboards.

    Thanks for this excellent review. My next HSF looks to be definitely this Ultra 120 Extreme.
  • Gary Key - Wednesday, March 7, 2007 - link

    Thermalright has contacted us and the name of the cooler will now be the Thermalright Ultra Extreme. We will update the article shortly. Still no word on a ship date but it should be shortly.
  • PICBoy - Thursday, March 8, 2007 - link

    Hi Gary.

    Just wanted to let you know there are still some traces of the name "PLUS" on the article. I hope this helps:

    * Page 1, last paragraph: "To isolate just the impact of the ***Plus*** modification we tested with the same Scythe S-Flex fan used in the Thermalright Ultra 120 review."

    * Page 2, Cooling Performance Test Configuration table: "Thermalright Ultra 120 ***Plus***"

    * Page 2, last paragraph: "Results with the Ultra 120 Extreme should be even better with the extra cooling provided by the additional heatpipes in the ***PLUS*** design."

    * Page 6, fourth paragraph: "We don't know the final selling price for the Thermalright Ultra 120 Extreme, but unless it is a lot more than the Ultra 120 you should definitely opt for the ***Plus*** model."


    By the way, can we expect a cooling review for next week also? That's all. Keep up the good work!

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