We 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!
- 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.