I've been experimenting for the past few weeks with ways of cooling my Duron 600@950 (around 950, I've played with that too). The Delta black label fan on a PAL6035 does an excellent job, but I can't stand the noise. The answer I thought was an 80mm fan on the heatsink. I bent up aluminum and glued pastic together in various shapes to make 80-to-60mm adapters. All were bulky, time-consuming to make, sometimes fragile and always ugly 
As well, the cooling performance wasn't that great (usually 3-4C hotter than the Delta).
I've finally arrived at a simple and effective solution. To mount an 80mm fan on the PAL take a 80mm wire fan grill, turn it upside down and attach it to the PAL with 3 woodscrews. If you get the right size screws they'll thread down between the heatsink fins without bending things out of shape too much. I put washers between the grill and the heatsink to raise the grill off the heatsink about 2mm. Next slip a couple 1.5" carriage bolts (1/8" diameter) up through the mount holes on the grill and attach the 80mm fan (with nuts). I used only two -- on diagonal corners of the fan. My fan is set to suck air away from the heatsink.
Next I ducted the 80mm fan to outside the case. I made an 80x80mm (inside) duct that slips over the fan and exits through the side cover. Now with an extra fan drawing air out of the case, more intake was needed. I added a quiet, low-cfm 80mm to the bottom front area of the side panel. The 80mm on the cpu is much more powerful than this fan, but its output is reduced by the drag of the heatsink and I don't run it full speed -- so the two fans more or less balance.
In addition I have an 80mm intake bottom-front and 80mm exhaust top-rear. I wired these two fans together on a 7v/12v toggle. I wired the 80mm CPU fan to a second 7v/12v toggle.
Results? With both switches to 7v position I idle at 33-34C. With Prime95 or Seti I'm usually at 35-38C with room temperation at 18-20C. And it is SO SO quiet!!
[Note: I'm using a temporary cardboard side cover, with a cutout for the CPU duct and the extra intake fan mounted on it. When I get up the nerve I'll cut the real cover ]
As well, the cooling performance wasn't that great (usually 3-4C hotter than the Delta).I've finally arrived at a simple and effective solution. To mount an 80mm fan on the PAL take a 80mm wire fan grill, turn it upside down and attach it to the PAL with 3 woodscrews. If you get the right size screws they'll thread down between the heatsink fins without bending things out of shape too much. I put washers between the grill and the heatsink to raise the grill off the heatsink about 2mm. Next slip a couple 1.5" carriage bolts (1/8" diameter) up through the mount holes on the grill and attach the 80mm fan (with nuts). I used only two -- on diagonal corners of the fan. My fan is set to suck air away from the heatsink.
Next I ducted the 80mm fan to outside the case. I made an 80x80mm (inside) duct that slips over the fan and exits through the side cover. Now with an extra fan drawing air out of the case, more intake was needed. I added a quiet, low-cfm 80mm to the bottom front area of the side panel. The 80mm on the cpu is much more powerful than this fan, but its output is reduced by the drag of the heatsink and I don't run it full speed -- so the two fans more or less balance.
In addition I have an 80mm intake bottom-front and 80mm exhaust top-rear. I wired these two fans together on a 7v/12v toggle. I wired the 80mm CPU fan to a second 7v/12v toggle.
Results? With both switches to 7v position I idle at 33-34C. With Prime95 or Seti I'm usually at 35-38C with room temperation at 18-20C. And it is SO SO quiet!!
[Note: I'm using a temporary cardboard side cover, with a cutout for the CPU duct and the extra intake fan mounted on it. When I get up the nerve I'll cut the real cover
]
