I have a couple of GbE cards, and installed Alteon AceNIC in my PCI Cage (maxed out Octane2).
It turns out the computer would crash with PCI errors after not too long time of use - but it worked just fine with the cage pulled off.
Then I opened the cage, and the chips Alteon seems pretty hot, including voltage regulator - all of them have heatsinks.
I did check and the fan in the cage spins correctly, and now I wonder - does Alteon get that hot normally (touching it was unpleasant, let's say it could have been around 50 deg C.
Now I replaced it with SGI Tigon3 based card (no heatsink) and the machine works with no issues...