Hardware Canucks: Benchmarkers Guide to the Phenom II

We will now really put this setup to the test and see how it handles temperatures as cold as -196C. Just the thought of being able to run LN2 all out on AMD is a bit weird for this overclocker. AMD has had cold bug problems for as long as I have been running sub-zero so it has just never been on the menu before. The phase results show this setup can handle -50C no problem so we are certainly optimistic going into this section. As always though, first some photos of the setup during preparation.



Our base layer of insulation remains the same for preparing the motherboard to run even colder than -50C. It held up remarkably well during the phase testing so we are set there. We then simply stack another layer on top of that like we did with the phase change cooler but instead of the evaporator, the base of the CPU pot goes through these layers. We then start with our tube donuts, the hold down, and the top sleeve for the tube. This entire assembly then gets a single wrap of paper towels in case any condensation forms between these layers. The paper towel is actually a heavy duty shop towel and is the standard now for sub-zero insulation thanks to Vince (AKA k|ngp|n). This entire setup then gets another Armaflex sleeve that encloses the entire setup.

Insulation prep for LN2 was as easy as the phase setup and again, we can't do anything but praise the Gigabyte GA-MA790GP-DS4H for its ease of insulation. One other item to mention is how well the motherboard has held up until now. This will be the ultimate test but the Gigabyte board has been flawless in our merciless beating and hope this trend continues. With the pot setup, it is time to bring temperatures down and get to work.


We can't really see the temperature in the first photo but we just cracked 0C and are heading down. In the second photo we have this great shot of -100C, but unfortunately this was with an un-responsive system running in the background. Somewhere are -80C at the base of the pot, the processor "bugged" out. This is the famous cold bug we have been praying was gone. As it turns out, the cold bug on our processor wasn't too kind to us and to be honest, anything colder than -60C initiated odd occurrences of the system.

Anything from the system freezing at random times to AMD's AOD software causing issues. The only way to reach the clocks we did was to boot at a low multiplier then raise the CPU multiplier within Windows with AOD. Unfortunately, with AOD freezing whenever it felt like, overclocking under LN2 became a tedious battle in futility. Opening CPU-Z, or SpeedFan would sometimes freeze the system after running a 5 minute benchmark where the system was completely stable. Needless to say, our results weren't as "ambitious" or promising as they were on the phase setup. Let's look at those results first, then we will discuss this overclocking battle a little bit more.

CPU-Z Validation click for full size... CPU-Z Validation
Super Pi 1M click for full size...	Super Pi 32M click for full size...

Yeah, not quite what we were hoping for. We basically got some SPi work done and a CPU-Z validation then the system went all haywire. We have had subsequent attempts at LN2 cooling on this setup and each time the results are the same. Anything past -60C is just cold bugged and things get all kinds of weird. The known information about clocking Phenom II under cold is that HT link must stay low, below 1000MHz. The other known is that not many chips can clock HTT when at a certain temperature. Our chip is one of those that just can't clock HTT past -50C pretty much. It really seems weird seeing what we were able to do with the CPU under our phase change system.

Clocking HTT or HT were absolutely no problem at -50C, but with a pot temperature of -60C neither want to clock. AMD "users" have been talking in forums lately saying AMDs latest batch of retail chips have solved the low clocking HT when sub-zero. This is great news as 3D performance does suffer with HT below 1000MHz. Not that there is much point, but here is a chart of the clocking like we say with the phase and air cooling.


We will hopefully be back with some more retail AMD Phenom II processors in the near future with the exact goal of clocking under LN2...with favorable results. Today, however, we have to pack it in and accept that our sample just doesn't like much past our phase change system temperatures.