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Long time ago after my last article was posted.Since I have overclocked pentiumIII 450@648 with Aopen AX63 pro,I never did it more with my Abit Bx6-2. Athlough I changed the board to Abit BE6-2 ,the failure still occured.So I have the question in my mind that what was the exactly cause of failure.The most propable cause may be the mobo. So I decided to get the new one.The MSI 6163 pro was my choice because of it stablility at high bus speed and supporting overclocking with adjustable many bus and Vcores adjustment. My decision was right,with my super cooling and a stable board,I can overclock pentiumIII 450@698 MHz. at 2.4 volts and the core temperature was -39 c !! .Let's see the setup system and the results.My System
PentiumIII 450 Sl37C Malaysia. Mainboard : MSI 6163 pro. Ram: Micron pc 133. Vga :Voodoo3 2000 pci. Harddrive :Sumsung 2.1Gb. Sound card :Sound balster live value. Power Supply : 300 watts ATX. The Cooling
This time I made an aggressive cooling.With water block 2" * 5" for cooling the entire pcb and its' cache and a cold plate made of aluminum as the same size as water block.I used two 72 watts peltiers to cool down the cold plate and use water circulated to cool the hot side of peltiers.But this time I did difference .By using phase change refrigulator to cool the temp down.As you known that the much you cool the hot site.The more you get from cool site. I use the compressor rating at 1200 BTU that is enough to cool the 12 lites of water down to -10 c easily.I also concerned about freezing water so I got antifreez too but I didn't add it because it was no need to decrease the conductivity of water by adding antifreez.All I wanted to do was observed the water whether it freezed or not if it freez I will add minimal quantity of it.In moving water is slowly to freez although its' temperature is below freezing point. In my project I didn't add antifreez to my water reservior.
This picture shows the water reservior.It is about 12 lites of water.I didin't add antifreez in it because I want to look how it go. How much is it cool?As tested the water temp in reservior could went down to - 20c.And when I started the machine the ice got around the interior wall immediately.This is too cold.This sytem is just for test only and I must looked for it's results and solve the problem in my real machine.I still impress this cooling very much.The cooling water then ran from reservior to the water block which attatched to pentiumIII450 pcb with two 72 watts tecs between it and a cold plate made of aluminum. When I started the power for tecs the ice was seen around the cold plate in a few minutes.
I didn't insulated it yet.As you see the ice was around the cold plate ,that was very thick but it caused no problem. Because in heavy loaded .the temperature still below freezing point.The temperture in MBM4.13 showed the internal temperature diode at -39 c (done in Asus p3c2000).And the temperature of the cold plate was about -15 c at the first time and arised to -32 c with no insulation. I think that if I can insulated that will prevent the heat loss,the temperture will get lower.The longer time the more cooling was reached as I noticed that the temperature still drop with time.The maximun temperature that I reached but didn't show in scrren shot was -42 c. My system is cool as Kryotech but seem too cheap than them.
Overclocking Result
First time ,when I overclocked this PentiumIII450.I could did it at 648 MHz. with Aopen AX63pro at 2.2 volts. with HSF.With Abit ,either Bx6-2 or BE6-2 it could be done only 620 and 630 resprectivly and its' stability was bad.So I didn't recommend you these boards if you want to overclock at high bus speed.What is the boards that good for high bus speed ? I think Asus P3b-f and MSI 6163 pro are good but I choose MSI because of higher bus speed at 155 MHz,Asus is only 150 MHz.I got the right choice with MSI I could ran the system at 675 MHz at 2.4 volts. My ram is Micron pc133 can run fine at 150 MHz. and Voodoo3 2000 pci done its' job best .and it can do at 162 MHz too.The next step was 155 MHz FSB,Micron ram couldn't booted as most pc133 ram that do best only 150 MHz. How to tweak this point?At high bus speed ,it draw the current back from ram so increase Vcore to chipset from 3.3 to 3.6 volts will help this.So I increase the voltage to 3.6 volts the ram could run fine at 155 MHz. At 698 MHz the system rocked a solid .I could ran seti@home many hours with no problem.Do you think like me that the chip can go further? yes I think so I changed the board to Asus p3c2000 which support pc 133 and more higher FSB. It support Agp divided at 1/2 , ram at 3/4 and FSB to 180 MHz. but only 2.4 voltage for slot 1 cpu.I think I can break the 700 MHz. but seem it needed more voltge than 2.4 volts.I tried to tape the pin but fail to increase it. Only maximum speed that I could do is 698 MHz.at 2.4 volts with defalse l2 latency.
Below are some benchtest and cpuid of PentiumIII450@698 MHz.
