Hmm....about 3.1:
- Hottest...
- In idle uses more power than any other mac pro...
- Does not have same PSU as 2.1 and 1.1 (more amps on 12V rails), and different cabling.
Worst of all 3.1 has most PSU failures...
- FB DDR2 800 - HOT! cause of many dead RAM risers...
Advantage that 3.1 has over 2006/2007 models is 64-bit EFI and a little bit faster PCIe.
And one other thing 2015-2008=too old + vintage status.
Way to make Mac Pro 3,1 (2008) systems cooler is to use 667 MHz DDR2 FB memory . The heatspreaders on the official 800 MHz modules are cool looking but worthless .
Also, re-thermal pasting the CPU(s) , GPU and northbridge chip every three years helps a lot !
And the number one reason for Mac Pro PSU failure is internal excessive dust build up. Blow out the dust on a regular basis (once or twice a year) , and the two contact plates inside the PSU will have enough of a solid contact to operate normally .
I actually serviced a sporadically failing Mac Pro for an Apple Tech once (of all people) and it was one giant dust bunny inside . After two hours of thoroughly disassembling and cleaning her, she ran normally again . That's all I had to do . Tech was lazy ...
Vintage and obsolete are Apple service designations . I estimate a Mac Pro's operational life at between ten and twenty years due to the quality of the components and solder used at the factory . I still have desktop "pro" Macs from 1987 purring along just fine . I collect and maintain Apple's high end computers , so I get a good idea about the longevity of these products . Consumer and small form factor stuff does not last as long .
Just keep everything clean (dust free) , cool (fans working and new thermal paste on all pads) ,power protected (power (voltage) line conditioner and surge protector) and replace the occasional failed part . You'll think she's immortal . I still service G4 PowerMacs for four of my clients . It's like being the Maytag repairman - little to do .
Three things in our (Mac Pro user's) favor : there's never been an official or secret recall and no sign of metal whiskering yet . Knock on wood....a miracle .