Insulating The Super Cool CPU Is One Of The Key Issues
Cooling a CPU down to -50 ºK below the freezing point of water requires a very well done isolation from the surrounding. You can certainly imagine that otherwise all the liquid in the air around it would instantly freeze at the CPU and the components around it, further away condensed water would cover the less cold components of the motherboard and this would definitely jeopardize if not even destroy any computer system due to short cuts. Thus the CPU needs to be isolated very well and to avoid any condensing water, the cover of the CPU should even be heated. So far Kryotech achieved this by putting the cooled Socket7-CPU inside a special capsule, which would plug into the Socket on the motherboard. The big disadvantage of this procedure is that the CPU is not directly plugged into the Socket, so that the signal way through the capsule was getting about one inch longer than it was supposed to be, which caused a lot of failures. I received a system with the old capsule technique last year in December, but because the system never ran NT nor any kind of SCSI device I declared the system as too unstable and declined from writing a devastating article about it. Kryotech has done a lot of work since then, and now the new 'clamshell' technology allows the CPU to stay right where it belongs, inside the motherboard socket. The isolation is achieved by placing the 'capsule' right onto the motherboard and another isolation layer underneath the motherboard, right under the CPU. This way the system runs rock stable and you can go ahead overclocking it.
Tom's Custom Super Cool Celeron
As already said, when I received the Kryotech Cool K6-3 500 system I wasn't too impressed by its performance, because it wasn't too far away from a normal K6-3 450 system and also because the K6-3 is still not exactly the fastest CPU for 3D-gaming. Thus I really wanted to run an Intel CPU at speeds way beyond its specifications and so the only useful CPU turned out to be an Intel Celeron CPU. We all know that all Intel CPUs are today shipping with a multiplier lock, so that it is impossible to run any of those CPUs faster than its spec unless you change the front side bus speed. Doing this with a Pentium II or Pentium III wouldn't let you go very far, because you have to make sure that the AGP clock doesn't exceed 75 MHz, unless you want to have trouble with 3D-applications. A FSB of 133 MHz may sound nice and will certainly be interesting in the future, but with today's Intel chipsets the AGP clock is at least two thirds of the FSB and no modern AGP 3D-card will run 3D-applications at an AGP clock of 88.6 MHz. Thus the decision had to be clearly against a Pentium II or Pentium III CPU. The story is a lot different with the Celeron. This CPU is currently still supposed to run at 66 MHz FSB only. If you raise the FSB to 100 MHz in a BX-board, you can run 66 MHz AGP clock and still overclock the CPU by 50%. The other beauty of Celeron is its low price. Running a Celeron 400 (6x66 MHz) at 600 MHz (6x100 MHz) would result in a CPU performance that's way beyond anything shipped by Intel right now and this at a price that would make the investment into a Kryotech cooling unit worth while indeed.
The Kryotech device that's placed onto the K6-3 CPU to cool it down to -50 ºC, called evaporator, had logically the size of a Socket7-CPU. It was fixed pretty much the same way as a normal heatsink/fan-combo is mounted to the Socket7. Luckily Socket370 has the identical dimensions of Socket7, so that it was easy to attach the Kryotech K6-3 cooling system to a Celeron for Socket370. To run this CPU in an Abit BX6 rev.2.0 motherboard I was using Abit's Socket370/Slot1 converter card, isolated it as good as I could and 'voila' I had my super cooled Celeron system. It turned out that isolating the Socket370/Slot1-converter card was a lot easier than isolating a special area on a Socket7-motherboard, as done by Kryotech in the K6-3 system. I simply isolated the complete card and didn't have to worry about any frozen or condensed water anywhere.
618 MHz Is What You Get
First of all I tested all the speeds that I could reach and was at least a little bit disappointed that there was no way of running the Celeron 400 any faster than 618 MHz (103 MHz x 6). It seems that the current design of Intel's 0.25 micron 'Mendocino'-core doesn't allow any higher clock speeds. A Celeron 433 would also not reach 650 MHz. Still 618 MHz is way beyond 500 MHz of a Pentium III and the system ran all the Quake2 demos continuously with 'timedemo' set to '1' for more than a week without a crash, actually the week when I was at CeBIT.