I (and my brother) had to hastily (i was trying to write a thesis at the time ) make a new block a few weeks back when my old one started leaking on my graphics card . Luckily after reseting itself a few times when there was water on it the card seems fine . Anyway the old block was made of aluminium and copper (all other components in the system being copper). As a few guys here warned me Aluminium and copper are not a good mix in a water cooling setup and as you can see here the corrosion had built up between the block and the lid and pushed the relatively thin lid away breaking the seal and allowing water to leak out .
After around 8 months without changing the water the corrosion was pretty bad. The amazing thing was that the CPU and block temps were nearly as good as when I first fitted it . This old block was made out of a solid lump of aluminium which was drilled and hacked out in the center (in the absence of a mill ). This looked very messy but actually worked very well .
We decided to go for an inline water flow through the block with the water entering one end and flowing straight across the chip area and then out the other side. The block was built up from 3mm copper as we had no access to a mill. Still with a bit of work it was possible to get everything fitting together tight and accurately for soldering.
Ready to be soldered with solder in place.
The widest bit of copper we had was 30mm so we had to make up a brass frame to rest on the CPU load pads. The frame bolts to the block and the side bars fit flush with the face of the block. It was a bit of a pain but it will make the block easier to convert to a GPU block when I get a Athlon64 .
Cleaned up block showing the 1mm copper fins which were designed to channel the water and provide more surface area for heat transfer.
Here you can see it attached to the brass frame which rests on the CPU load pads.
Finished block with 8mm ID tubing attached.
As for performance it was slightly disapointing (not as good as original corroded block ) at first but they seem to have got better over the las few weeks which is strange. There may have been air trapped in the block or something but anyway the block is now around 5 degrees above room temp and the cpu a few degrees above that. At the mo the CPU is at 19C but the room is freezing (around 10C).