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: 2.20V
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 Swiftech H2O-120 Compact and Corsair Nautilus 500 both topped out at 3870 MHz - near the top of tested air coolers but below the 3.94 GHz of the Thermalright Ultra-120 eXtreme, and the 3.90GHz of five tested air coolers. Once again test results - this time in overclocking - are near the top but do not match or exceed the best air coolers tested at AnandTech.

It was quite a surprise to find overclocks on the P35 motherboard also topped out at 3.87 GHz, particularly since we could not duplicate the 14X base multiplier on the ASUS P5K Deluxe motherboard. We achieved 3.87 GHz by choosing the 333 strap and setting a FSB of 352 with the 11X multiplier. This turned out to be the highest stable overclock on the P35 board with either water cooler - the same results found on the EVGA 680i board.

As stated many times, the overclocking abilities of the CPU will vary at the top, depending on the CPU. This particular CPU does higher FSB speeds than any X6800 we have tested, but the 3.9GHz top speed with the Tuniq is pretty average among the X6800 processors we have tested with Tuniq cooling. A few of the other processors tested with the best air coolers reach just over 4.0GHz, but the range has been 3.8 to 4.0GHz. Stock cooling generally tops out 200 to 400 MHz lower, depending on the CPU, on the processors tested in our lab.

Scaling of Cooling Performance Final Words
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  • rallycobra - Monday, September 17, 2007 - link

    I'm building a new quad system, and I was going to go with the swiftech kit, and upgrade to a 120x3 radiator in the future. For now, I'm going to stick to air.

    Can you run the test again with a quad? Another site says that the swiftech outperforms all air solutions, but I trust your methodology a lot more.

    Watercooling is elegant if you have the radiator outside the case, and you can cool the cpu, chipset and vga. It keeps the inside cool, and gets all of the heat out.

  • aigomorla - Monday, September 17, 2007 - link

    Your upgrading to 3x the cooling power this article previewed.

    So if there saying a 120x1 will match a ultra120extreme, your saying 3x that cooling power isnt worth the migration.

    *scratches my head*

    This is what i mean about this article screwing people up in water migration.
  • poisondeathray - Monday, September 17, 2007 - link

    Thanks for the interesting review.

    Given the increasing prevalence of quad-cores, it might be interesting to repeat the tests with an overclocked quad core configuration.

    Although the testbed was different, at least 1 other hardware site got better results with similar watercooling vs. Tuniq.
  • gingerstewart55 - Monday, September 17, 2007 - link

    I wonder what was wrong with your setups and your pumps. Having had the Corsair Nautilus 500 unit, and the pump the Swiftech kit is based upon, something is/was seriously wrong with your setup or pumps.

    The Corsair unit's fan, at least in the one I used, drowned out the pump completely.

    The Laing pump in the Swiftech kit, the same pump in the Corsair kit by the way, is sitting in my computer and is utterly silent....completely drowned out by any of the four fans in the case....three Scythe S-Flex "E" fans, at 22 dBA on full speed, and an Antec SpotCooler on lowest speed (the Antec is the loudest fan in the case, btw.)

    I'd almost hazard a guess that both kits, after being set up, still had a bubble/pocket of air in the pump. The Laing pump can get quite noisy if no completely bled of air.

    Otherwise, there was a mechanical fault in both your kits' pumps as the Laing is almost completely silent when working as attested to by the hundreds of people using those pumps and hearing absolutely nothing from them when being used.

  • Nickel020 - Monday, September 17, 2007 - link

    You need at mod top for the Laing pump, it's unbearable without one, but if decoupled almost unhearable with a good top.
  • Wesley Fink - Monday, September 17, 2007 - link

    We tested both systems as provided by Swiftech and Corsair. Both units are provided as complete kits and both manufacturers are familiar with our cooler test methods.

    Modding everything we test defeats the purpose of our comparative testing.

    We are not finished with water cooling reviews, and we will be reviewing more water cooling systems in the future.
  • Nickel020 - Monday, September 17, 2007 - link

    That's not hwo I meant it, of course you shouldn't mod the kits for testing. I was just saying that the Laing is not a bad pump for custom setups, in fact, it's pretty much the best pump for most setups if you use a mod top, which makes a big difference. I don't think I've ever seen a pic om someone using it without a mod top, but dozens with all kinds of mod tops.
  • Wesley Fink - Monday, September 17, 2007 - link

    I first thought there was a pump defect as well. So I acquired FIVE Apogee drive blocks from different sources and all measured similar dbA noise levels. There was also the 6th pump in the Corsair Nautilus 500.

    Subjectively the pumps were relatively quiet because the noise frequencies appear to fall in a freqency range that is not particularly annoying. However, our standard sound meter said measured noise was pretty high. We stated this in the review and also commented the pump noise was not annoying to our ears, but it may be to others. Measure the noise of your system and let us know what you find.
  • psychotix11 - Monday, September 17, 2007 - link

    These two set-ups do not represent the top end of water cooling. It's long been past the point where a single 120mm rad is enough for a CPU.

    Toss these out and replace them with a custom set up with a dtek fuzion CPU block, 2x 120mm fan rad, ddc pump with petras top, and 1/2 id tubing and then see where it gets you.

    Also liquid cool the chipset and then see if stock air can keep up (after), it won't.

    You're taking two premade kits made for the user that has never water cooled before. It's simply not in the same category as the higher end custom kits.
  • Wesley Fink - Monday, September 17, 2007 - link

    We did not state water cooling was always inferior to the top air coolers. We said, based on these test results and others we have run recently, that you would need to spend more than $300 on a water cooling system that might outperform the best air coolers.

    At more than 4 to 6 times the price of a top air cooler most readers would not conseder that good value.

    I actually agree with your comments, but please tell us the total cost of the water cooling setup you say is needed to beat the best air coolers.

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