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Overclocking the AMD Phenom II at -30°C

Overclocking the AMD Phenom II at -30°C

amd_logoWe didn’t have much time to spend with our shiny new Phenom II X4 940 processor and really wanted to do some more serious overclocking with it. As you have undoubtedly heard, the Phenom II loves the cold, loves voltage and has significant frequency headroom. Though we definitely confirmed that last point, achieving an impressive 3.8GHz on higher-end air cooling, we wanted to push it farther.

Back in 2006, we reviewed Asetek’s very impressive Vapochill LS phase-change cooling system. Able to hold the evaporator head’s temperature as low as -60°C in idle, it is in a league all of its own. Admittedly, the Vapochill LS was designed with single core processors in mind, but it is still the most powerful, mass-produced, and commercially available cooling system around. As Asetek was kind enough to send us an AM2 mounting kit, we set out to see how the Phenom II does under the Vapochill LS!

System Configuration

  • AMD Phenom II X4 940 Black Edition (3.0GHz Default Frequency)
  • Asetek Vapochill LS with AM2 socket kit. Fans @ 100% and Heaters @ 75%.
  • MSI DKA790GX Platinum Motherboard (AMD 790GX Chipset)
  • 2x1024MB Corsair XMS2 PC2-8500 Memory
  • Western Digital 320GB SATA2 Hard Drive (WD3200AAKS, 7200RPM)
  • 2x ATI Radeon HD3850 Video Cards in Crossfire-X mode.
  • Corsair TX750 Power Supply
  • Pioneer Optical Drive

We began by prepping the MSI DKA790GX motherboard.


Asetek provides everything necessary to prevent condensation, which is the biggest danger when using below ambient cooling methods.


Even the Vapochill LS back plate has an integrated 12V heater to prevent ice from forming at the rear of the motherboard and socket. Since this configuration was only going to be used briefly for testing, we didn’t bother applying dielectric compound into the socket pinholes.



A thin layer of phase-friendly thermal interface material was applied over the CPU’s heat spreader and the head was attached to the board. A caseless installation of the LS can be quite messy due to the heater leads, the external control board, and various other connectors, but this was the best way to have access to our hardware in a hurry.


We powered the unit on in an 18°C room and watched the evaporator temperature slowly settle to -60°C. It was clear that AMD’s new 45nm technique has done away with sub-zero instability or the infamous “cold bug” that plagued both their 90nm and 65nm parts for years.

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  1. BuddyJ
    BuddyJ Nice job Mike. Do you think you could have gone faster with a different board/BIOS, or is it just the chip's heat that's maxing out the OC?
  2. Thrax
    Thrax Heat is certainly a part of the equation if the LS' evap head is approaching -30C. I also think it's an architectural limitation which is often characterized by excessive voltage requirements for insignificant gains.
  3. fatcat
    fatcat Nice article Mike. Yea seeing a PhenomII at 6.3GHz on Liquid Helium @ -240C was a sight.
  4. Komete
    Komete Good work. When you ran some benchmarks, how did they scale? ANy noticiple difference between 3.8ghz and 4.4?

    Also I know hyper transport didn't have much of an effect on overclocking but did cutting it diminish performance? I'm curios to know, when overclocking the phenom 2's what is the goal to get the most out of the chip.
  5. lemonlime
    lemonlime Thanks, all. I didn't have a chance to run any benchmarks as my Windows install was borked along the way and I had to reformat and reinstall. I've still got the rig assembled as pictured, so I'll see if I can run a few quick benchmarks to check for scaling :)
  6. BuddyJ
    BuddyJ Benchmarks plz!
  7. zeo 1 pretty nice indeed I've been a fan of amd since the start hell one of my first stand alone pcs was an amd back in the days of slot kit :D
  8. Mike L. So, not to Bash On you guys running the OC, But.....i have to say you guys did not try hard enough/ Or got a bad chip. I myself have a phenom II 940, currently on a simple H2O setup i have a 24\7 stable of of 4009Mhz 1.5Vcore and a suicide run of 4.4 1.55Vcore (boots up but BSOD as soon as i try prime95)

    i think if you guys got another chip/ or tried again with the Phase you could get a stable 4.5 at a 1.6Vcore
  9. lemonlime
    lemonlime Thanks for the comments, Mike L. I agree that our chip is probably not the greatest. Your result on water is significantly better than we saw on above ambient cooling (I only managed 3.8GHz at 1.55V). I spent quite a few hours with the rig, so I'm pretty confident that I didn't miss anything. It was really tough to find a 100% Prime95 stable clock speed and had to scale back quite a bit to retain 100% stability. I was able to get some pretty impressive clocks without worrying about Prime95 stability, but 100% stability painted a very different picture.

    Hardware Canucks did a good Phenom II overclocking writeup as well and saw similar results on phase. Their highest CPU-Z validation was about 500MHz higher than their 100% stable 3DMark Vantage benchmark.
  10. BuddyJ
    BuddyJ Mike L, welcome to Icrontic. What board are you running to hit that OC? ASUS? I'm grasping at straws ...
  11. Thrax
    Thrax If those are your scores, we definitely got a bum chip. Them's the breaks, I suppose. I'd be really interested in seeing pictures of your setup and CPU-Z! :)
  12. Komete
    Komete What OS were you using? I'm reading some very interesting things about vista64 bit getting less of a top end overclock than 32bit xp. I'm wondering if it extends to all the 64bit os's.
  13. lemonlime
    lemonlime For this particular test, I was just using 32bit Windows XP. I've heard that too.. Vista 64 is a little more finiky about system stability.

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