[cyberman]

I've recently recieved a PowerForce G3 cpu card (i.e. old style, pre-g3 pci powermac) from powerloigx as a replacement to a powerlogix powerboost 200mhz 604e card that died under warranty. The heatsink the powerforce g3 came with was, much to my dissapointment, rather small. Basically, it only dissapates enough heat for the card to run at its rated speed of 220mhz; any higher and it overheats (until I put in a fan; see end of message).

FYI, this is a PowerMac 8500, originally with a 150mhz 604 cpu. It has run at its stock bus speed of 50mhz for eternity, 1st with the original 150mhz 604 and later with the powerboost 200mhz 604e until that cpu died.

What I'd like to know is, is there any body that sells the huge heatsinks that powerlogix uses on their higher speed cpu cards (not zif cpus, but old style cpu cards)? Also, I looked at apple's heatsinks, but it doesn't line up with where the screws go in and where the clips attach to cpu card.

P.S. Why don't I install a fan, you might ask? I already did: I put in a 12v, .13 amp, 4 inch fan and connected it to the 5v wire on one of the power connectors inside the mac and its still too loud. Anything more powerful would almost certainly be waaaay too loud for me. I figure a massive heatsink will be more than enough.

[RoofusPennymore]

Even with a massive heat sink you need air flow over that thing. You may be forced to use some sort of fan. Have you tried improving overall flow in the case? I don't know how the 8500 is arranged but my PowerCenter 150 has a fan in the back for a CPU and one for the power supply. If all you have is a fan for the powersupply then see if you can arrange the air movement so that it flows over the existing heat sink.

[cyberman]

There is most definately ariflow over the cpu. The inside of the case appears to be designed specifically for proper airflow. The original apple cpus that went in 8500's had massive heatsinks on them (nearly identical identical to the ones on some of the powerlogix cpu cards) and ran hotter than current G3s. Thus, if I can find one the powerlogix heatsinks, cooling should improve by some amount, no matter how small and with no increase in noise. he 8500, by the way has only one fan: inside the powersupply. It provides sufficient cooling for the entire case, unless you overclock your cpu. As I'm overclocking my cpu, the power supply fan and skimpy heatsink on the g3 don't give me much room.

Incidentially, I put some of Radio Shack's thermal compound on the heatsink and reatatched it to the card. After maxing out cpu usage, the reported cpu temp was a few degree's cooler than without the compound.

Basically, I'm aiming to increase cooling as much as possible without increasing the noise level. Then I'll try and find a real quite cpu fan.

[RoofusPennymore]

You might try and replace the fan on the powersupply.