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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  • Visual - Wednesday, March 7, 2007 - link

    now it's time that someone combines this 6-pipe ultra with a "TEC" or whatever its called in its base
    what could the results be....
  • Lord Evermore - Monday, March 12, 2007 - link

    Probably worse, or at least no better. The contact area of the TEC with the cooler is limited to the size of the cooler base. That's not a heck of a lot larger than the contact area of the CPU itself, and assumes you could actually fit in a TEC to cover the entire heatsink plate. A TEC generates heat, it cools one side, that heat is put out on the other side, plus extra heat from the energy used by the TEC. So you'd have more heat (and of course, the more energy used, the better the cooling, and the more excess heat generated) being transferred to the same or slightly more surface area of the heatsink. With equal contact areas, there's just no way for a TEC to actually provide better cooling. It might cool really well for a very short period, but then it would burn out if that heatsink contact wasn't able to carry away the heat well enough. If the heatsink can't cool the CPU down to ambient, it won't be able to cool a TEC any lower with the same contact.

    The old days of using TECs are pretty much gone, because of the issues involved. But when they are used, they're used in conjunction with a larger heatsink, both in contact area and radiating fin area. Or with liquid cooling.
  • Reynod - Wednesday, March 7, 2007 - link

    Nice review Wes ... liked it.

    Well done Thermalright ... good response to customer needs.

    Thermaltake should take a page out of this book and produce some decent stuff that works ... the emphasis on bling might be fine with noobs ... but they are off my shopping list as an overclocker
  • sephiros64 - Wednesday, March 7, 2007 - link

    is it confirmed that the new model will be the 120 ultra plus ? I'm sure a lot of consumers looking for this product will want this newer, better version and are concerned of the model number when ordering.
  • ceefka - Wednesday, March 7, 2007 - link

    I am still hoping for a review of this model. I want to cool my CPU fanless. The airflow is already taken care of with two Nexus 92mm intake fans @5v and 120mm Antec Tricool (low rpm) exhaust fan.

    Is that S-Flex fan also suitable to operate as case exhaust fan?
  • Wesley Fink - Wednesday, March 7, 2007 - link

    If your case can mount 120mm fans the Scythe S-Flex will operate fine as a case exhaust fan.
  • Philxxx - Wednesday, March 7, 2007 - link

    Hi,
    im fairly new to custom building computers and i wonder if there is a performance change when the heatpipes are placed vertically vs. horizontaly like your picture indicates.
    From what i understand so far a heatpipe evaporates a fluid inside the pipe and uses the vapor to transport the heat away from the CPU. Would the heatpipes and the evaporation/condensation proccess behave different when the cooler is mouted vertically like in a tower? Any chance to test this senario?

    Regards,
    Philipp
  • Wesley Fink - Wednesday, March 7, 2007 - link

    From the Test Configuration (p. 3)of the Thermalright Ultra 120 review: "All cooling tests are run with the components mounted in a standard mid-tower case. The idle and stress temperature tests are run with the case closed and standing as it would in most home setups. We do not use auxiliary fans in the test cooling case, except for the north bridge fan attached to the 680i for overclocking."
  • yyrkoon - Wednesday, March 7, 2007 - link

    I can not help but wonder how much better all the coolers in your roundup would do with a 'better' fan. There are fans out there, with two ball bearings that will push 220CFM. Granted, if memory serves, these fans also exhibit 65+ dba noise levels, but it would be interesting to see the results.

    Barring a 220CFM fan pushing too much air ( dislodging a cooler in the process, heh ), I would at least expect minimal improvements.

    http://epowerhousepc.com/delta-120x38mm-tfb1212ghe...">Link
  • Ender17 - Wednesday, March 7, 2007 - link

    Any idea when this will be available?
    Or any word of an improved mounting mechanism for 775?

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