Big Lar to 1007 – Water Cooled Peltier

UPDATE 5/13/00

Big Lar found another use for the fridge – chilling results!


Water Block


Water Block

It all started a while back actually, with a P3 450 Katmai, but that’s another story. I run the PIII 650E Slot 1 CPU on an Abit BE6-2 with Bios Revision Beh_QY. I started overclocking the chip almost immediately, shedding the Intel heatsink and backplate within an hour knowing full well it wasn’t up to the rigors I would be putting it through.

I now use water cooling but started with the Alpha P3125. Quite frankly, I had two 650E Chips but my first ended its lifespan with a crack in the slug; this I believe to have occurred by cooling it to sub-zero temps with a 78 Watt Ice71 Peltier. When turning the computer off, I think the onrush of heat from the peltier against the existing freezing slug was just too much for it.

That was my week 1 chip. The chip I am using now is a week 50 SL3NR. I started with a clock to 910 (140 FSB) using my Peltier and a 1 3/4″ x 4″ x 3/16″ thick copper cold plate. I insulated it by surrounded it with a combination of meat packing and craft foam – I have found this combination works well in my quest to beat condensation.

System Specs:

  • Abit BE6-2 Motherboard
  • Intel Pentium III 650 Coppermine
  • 2 128mb sticks of Mushkin High Performance Athlon Tested SDRAM
  • Matrox G400 Max AGP
  • Adaptec SCSI 2940U2W Controller Card
  • Seagate Cheetah 10K LVD Drive (main drive) 9.1 G
  • Seagate Barracuda 7,200 rpm Drive (backup) 9.1 G
  • SBLive Value
  • Hollywood Plus Decoder Card
  • USR Sportster ISA V90/56K Modem
  • Pioneer 6x DVD Rom ( scsi)
  • Floppy Drive
  • Teac 32x CDROM
  • Digital Doc Temp Sensing Unit
  • 2 Hard Drive Coolers
  • Yamaha 6x4x16 CDRW


I use a home made aluminum water block, 1″ wide x 4″ long x 2″ high with 3/8″ brass fittings. This is now taking the heat from two Frost 74 Peltiers attached to my copper cold plate. I also use an inline cooler (pic below) made for me by a friend (Michiel) –
all being supplied by a 120gph Lil Giant Pump bought at Home Depot.

Water Block

My CPU temp averages -35 C to -41 C, even under a full load. The inline cooler consists of two water blocks, one that is cooled by two more Frost 74 Peltiers, and a hot block in which to absorb the heat given off by the two peltiers. I use this as I found after just running with one 5″ x 12″ radiator that my temps would slowly “creep” up.

The hot side is cooled by said water block and is supplied in a separate “loop” of it’s own with another Lil Giant 120 Pump. Both loops have an identical radiator to cool their respective water and have two 120mm Radio Shack fans blowing thru the two.

My Peltier “sets” have their own power supplies; one 250 watt 10 amp @ 12 volts for the Peltiers on the CPU and one 300 watt InWin power supply for the “inline” peltiers. My system uses a 400 watt Enlight power supply.

Both radiators have reservoirs for the pumps and the inline is housed in a separate Inwin Q500a tower. Case cooling for my Server/Tower consists of one 120mm 110 volt fan for intake, two 80mm Fans in the lower section of my case – both internal power supplies exhausting. My case temp never exceeds 26 C.

Bios Settings:

This is the interesting part: My settings are very average – just about all that deviates from the Normal Default Values is my AGP. I of course run at 2/3 but I am able to run it in the Fast Mode.


I am able to run up to 1000 MHz at default voltage; I need to bump it up to 1.7 volts to get to 1007 MHz. My CPU will also run at 1012 MHz, But not stable.

My RAM timings are CAS 3,2,2 at 1007 MHz and I am able to achieve 150 FSB at CAS 2,2,2.

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