Are there any issues with having six disk drives in a Mac Pro? I've recently turned my old early 2009 quad core 2.66 GHz Mac Pro into a file and media server. I have four 4 TB hard drives with content on them, and soon I'll be adding a fifth. Add in a 2.5" SSD for my system and that's a total of six drives.

Currently several of these drives are in their own enclosures. But in order to maximize read and write speeds (especially since the 2009 Mac Pro doesn't have any USB 3 ports) I was thinking of putting all of these drives in the Mac Pro itself: four in the drive bays and then two in the optical drive bays.

However, I'm worried that my old Mac Pro may not properly handle dissipating the heat generated by all five hard drives in addition to heat from the CPU and motherboard. I haven't ever replaced any of its fans. I'm also curious if there are other reasons making all of these drives internal might shorten their life.

Is this a reasonable idea? What are the issues that I should be aware of so I can keep everything running smoothly?
Purely anecdotally - I've been running 4 HDs in Mac Pros since 2008 with no issues - but never tried 5.

Currently I've a 4,1 with 4 HDs &amp; a boot SSD in the optical bay. I still have the optical in the other bay.

I find that normally the CPU fans run a little fast at stock settings, so I use iStat Menus to lift the Intake fan speed from its nominal 600 to 1000 rpm &amp; that settles everything down.

Pure speculation, but that's because I'm running 2x3.46Ghz Westmere Xeons instead of the original Nehalems, so ymmv.

The only thing I'd beware of would be to give it enough room to breathe, plenty of exhaust space. I find my older 3,1 whilst perfectly capable of keeping its own temperatures down, really throws a lot of heat into the room, so I wouldn't ever put it in an enclosed space.

Potentially, with an HD in the optical bay, you might want to lift the Power Supply fan speed, as the HD will be pushing more heat than the opticals ever would &amp; I'm not sure the system would automatically compensate for that.