Better Cooling for the DEC XL300 Alpha workstation

Okay, it is well designed, but it could just be that now that it is a few years old, it may have sucked in alot of cat hair and other junk, and that CPU just might be running hot as a pistol! The fan speed is also fairly low most of the time. This can be increased, with no soldering or irreversible wanton destruction.

Here's what I did.. You can do it too!

First, open the left side of the Alpha (On your left as it faces you). If you can't get this far, then the project is probably beyond your skill level. Leave it plugged into a grounded outlet, and always ground yourself to the case before touching anything inside, to reduce the opportunity for static electricity damage.

The nice CPU board is removed by first unscrewing the phillips-head-looking screw which is in the center of the rail along the side of the CPU facing you now. Once you do this, swing out the front and rear parts of the rail, and this will lever the CPU board out of its tight connector on the main board.

The CPU board is nicely made, and has a large heatsink on the 21164 Alpha processsor, and a duct for the heatsink cooling air. The bottom of the board also has a metal duct for cooling.

This large IC also gets pretty hot, and can benefit from this modification.

Looking carefully at the backside of the bottom part of the thick front panel assy, you can see a fan inside there, and what looks like a nice foam filter between the very front panel of the computer and the front of the fan.

If you look carefully, you can see a little thermocouple (the black thing with the white wires) attached to a plastic clip behind the fan, in the airflow path. This sensor tells the power supply how much electricity to send to the fans, depending on how hot it is in the room. The idea is to keep noise down, except when the extra cooling is warranted.

Here, the thermocouple has been removed from the clip, and is loose by its wires. Be careful not to pull on the wire. Note the small wire-tie at the fingertip. Cut the tie with some diagonal pliers.

This image is actually a sideways view of a small twist-fastener at the top innermost edge of the plastic grille at the rear of the fan. The fastener should be undone, and the thermocouple wires only removed from its embrace. Leave the red and black fan wires in it, or put them back in, if you had to loosen them all, to get the thermocouple wires out.

The fan and thermocouple wires run up beside the hidden side of the floppy and hard drive and then back towards the rear of the case. About halfway back, they go up through a hole with alot of other wires, into the power supply. The connector you se with the red, black, and blue wires is the hard disk power cable.

Your mission, Jim, is to get at the fan and thermocouple wires, pull them down towards the bottom of the case sufficiently to expose this wire tie to the diagonals. MOOOOOHAHAhahahahaaaa!! Poor wire tie! Cut it, and then unentwine the white thermocouple wires completely from the red and black fan wires. Put the fan wiring back. Take care not to let it hang down in front of the CPU board connector!

Now, there is plenty of wire length.

This is the tricky part. Using a special heatsink vane spreading tool, or a screwdriver, spread the vanes as you try to insert the thermocouple into a gap between them. Don't worry about trying to slide the thermocouple all the way down. It won't go, and you can wreck it, or the CPU board. All it has to do is be slid halfway into the vanes near the corner as shown. The CPU will provide more than enough heat to make them ol' fans speed up, you betcha!

Here is the shot of the completed mod. Now you are ready to compute with a cooler system, albeit a bit noisier. Ready for those summer months..

Ah, yes, the nice foam filter. Hey! That's no foam filter! It's cat hair!! Gross! Don't forget to remove the plastic front panel, and dust off the grilles, both at the bottom, and in the space over the CD drive, as that is where such accumulations take place.

Home © 1998 Pat Jankowiak