If your active-cooled drives are getting that hot, then something is very wrong with either your ambient room temperature (is it 40°C?) or with your active cooling.
Active cooling in a reasonable-temperature room keeps even 15K drives well under 40°C at full duty (closer to 30°C, really, according to our monitoring data I just looked at, the room is around 20°C). Keeping drives within 15°C of ambient shouldn't be a huge deal (though it can be noisy).
I've seen actively cooled 7K drives in my ZFS NAS start giving checksum errors while silvering (i.e. recalculating parity etc.) after replacing a bad disk; smartmon reported temperatures of about 60, IIRC. Using an LSI 8-port SATA controller, I was silvering a 4-disk raidz at a rate of perhaps 300MB/sec, and it was making the drives too hot. I had to fall back to the motherboard SATA connectors (and ~150MB/sec array throughput) to keep things cool enough to complete.