What problems have I had so far?

Some of the things -- expected and unexpected -- that [will] have cropped up.

Rivscrews -- what the hell?

The heatsink is attached to the processor with these interesting little things called Rivscrews.  They're rivet/screw cross-breeds.  They seem to have Allen or Torx heads.  They're meant to be somewhat problematic to remove, which is an annoyance.  It'll also be a pity to waste the heatsink; it's a socking great lump of what appears to be anodized aluminium, and it does a pretty good job of keeping the processor cool even without a fan directly on the processor.

Update 16/6/99: I've tried removing the heatsink.  The good news is that it's possible to unscrew the Rivscrews with Torx #8 screwdrivers.  The bad news is that the heads of two of the four Rivscrew weren't up to the job.  Their heads were mangled, and I'm going to have to drill them off.  This is a big pain.

Update 30/6/99: I've drilled off the remaining Rivscrews.  Examination of the thermal plate reveals that it's not very flat at all; it's full of cut-outs and things.  This means that it won't have good thermal contact with the peltiers, so is encouraging me to remove the thermal plate and replace it with one of my own creation.

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Thermal plate -- to remove or not to remove?

The Pentium II cartridge is designed in the following way.  There is a PCB (printed circuit board) that has on it the processor core, the cache controller, and a number of cache chips, as well as a few resistors and the like.  This is enclosed in a black case.  One side of the black case is made of a piece of aluminium (the other sides being plastic), and is called the "Thermal plate".  This piece of aluminium has certain raised areas, so that it touches the processor core, and, on some variants of the processor (but not mine), the cache chips.

I am going to remove the thermal plate.  This will require me to disassemble the processor.  It should be noted that the processors aren't meant to be disassembled.  The procedure will be a little risky, as there's a chance of snapping something that shouldn't be snapped.  I will try to take lots of clear pictures when I do this, as, although I have seen pictures detailing how to carry out the procedure, none of them are brilliant, and with luck mine will be better.

Update 16/6/99: Somewhat bizarrely, my thermal plate does appear to be in contact with the cache.  I don't think that it should be; I thought that was an honour that was only bestowed on Pentium II 450s, and the identical Pentium II 333 parts.  I'm now no longer sure if I should bother removing the thermal plate.  It doesn't seem to be as much of a necessity now.

Update 30/6/99: Due to the lumpiness of the surface of the thermal plate I think I will remove and replace it after all.  I have taken the opportunity to completely dismantle the entire cartridge.  I didn't take as many pictures as I had hoped, but I have some that have come out quite well.

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Bus speeds

Preliminary testing shows that my system has no problems with a 112 MHz bus.  I haven't yet risked going faster than that.  There's a chance that I'll trash a hard disk, which is not something that I want to do.  I'm not sure what multipliers I can use, so bus speed may be my only choice.  I know that I have multipliers up to 5, but I'm not sure how much beyond that they go.  Some experimentation is in order.

Update 30/6/99: I've tried the 117 MHz speed with the 1/4 PCI multiplier, at a speed of 3.5 × 117 = 410 MHz.  It works fine.  I've not ventured higher, however.

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Secondary cooling: the 440 BX chipset, VRMs, and video cards

One part of the 440 BX chipset (I think the North Bridge, but I can never remember which is which) is located essentially right underneath the processor.  At the moment it has a green heatsink on it.  It may need cooling, but that will not be too easy, as the water cooler will interfere with it.

My video card has no heatsink or fan.  I may have to invest in one some time; I will probably overclock the video card in the future, and if I overclock the bus speed much then it will probably need additional cooling anyway.

I will probably add a fan or two to the case to force air through it.  At the moment it has a reasonably good very quiet fan blowing air out the back of the case.  I'd quite like to get some airflow over the RAM and cards -- the EMU10K1 processor on the SoundBlaster Live! in particular can get very warm.

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Condensation

Condensation could be problematic.  I'll use foam insulation around the cold parts, which should solve most problems.  The actual cooler and processor will probably end up being in some kind of a big cartridge anyway, so there shouldn't really be any condensation anyway.

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The case

There's a slight aesthetic problem, in that I'll have to make holes in my case.  This will be a bit messy.  I'm planning on having a sort of quick-fit mechanism, to allow me to quickly separate the external part of the mechanism from the internal part.  I'm not quite sure how I'll do this.  One idea is to use Hozelock-type connectors, and bog-standard hose pipe.  I believe that there are connectors that self-seal when not connected to anything, but I don't think I'd have the water pressure for that to work.

The radiator and power supplies will be amalgamated into a single unit, as I reckon I can manage that quite neatly.  This way, the fans can blow over both the radiator and the guts of the power supplies.  It should look fairly neat when finished.

I've already had to replace the PSU in the case, as the Dell PSU uses non-standard connectors.  Even more irritatingly, the front-panel lights and buttons don't use standard connectors to attach to the motherboard, so I've had to implement a converter for them, too.  It's unfortunate that the otherwise lovely case should be hobbled in such a way.  But it's so easy to get in and out of that it was worth the effort, and the cost of a new PSU is much less than the cost of a new case.  Even if the new PSU does have a somewhat suspect fan that makes silly noises every now and then.

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