PC 4870 card's fan doesn't spin up in OS X?!

[Axonometry]

I have recently bought an MSI 4870 with 1 GB of GDDR5 (T2D1G model) in my Mac Pro, only for the purpose of using it in Vista and playing games.
I did understand that its not supported in OS X, and even if i use the stock (2600XT) card to boot OS X, it will spin its fans at full throttle.

I installed the 4870 in the first PCI slot, but i didnt have the proper power cables for it (only one mini6pin-to-normal6pin, and one 2x4pin-to-normal6pin) so i just tested it in Vista for a time, without even putting in the 2600XT and booting in OS X. Worked like a charm, with Vista automatically booting all the time.

But today i got my other 6-pin power cable, so finally i could close the side panel, and put everything in its final place, with the 2600xt in pcie slot 3 and the MSI 4870 in slot 1.

I booted os x for the first time since i installed the 4870 and for my greatest surprise, the fans are spinning at a normal, barely audible rate on it!!!

How is this possible, and is this a normal thing, ie. won't the 4870 overheat because of this, or something???

System Profiler says the following:

Should i be concerned, or just cheer, for i can now play games in Vista and use OS X without having to hear the very very loud fan noise?!

 

[Axonometry]

Okay, i went back to Vista to check up things, and saw that:

4870's GPU temperature and fan speed went up by 15% (65C idling, is that normal?)
catalyst control center reports that:

2600xt is "disabled hardware" and it is 65C with a fan speed of 1%.

What is the problem here, or what can be done in this situation?


Thanks

 

[DenniZ]

Okay, i went back to Vista to check up things, and saw that:

4870's GPU temperature and fan speed went up by 15% (65C idling, is that normal?)
catalyst control center reports that:

2600xt is "disabled hardware" and it is 65C with a fan speed of 1%.

What is the problem here, or what can be done in this situation?


Thanks

My X1900XT with 2x7600GT above it has a idle temperature of about the same. It should be ok though.