Question swapping cpu trays

[Lfrancosan]

Im new to the mac pros but so far so good, came from a imac but liked the way you can customize these its more my style.

I have 2 mac pros right now and will only be keeping one

first one is Mac pro 5,1
Processor Name: Quad-Core Intel Xeon
Processor Speed: 2.8 GHz
Number Of Processors: 1
Total Number Of Cores: 4
L2 Cache (per core): 256 KB
L3 Cache: 8 MB
Memory: 8 GB

this one has built in wireless 8gb ram and the radeon 5770 and a 1tb hard drive

my other mac pro is a model 4,1

Two 2.26GHz Quad-Core Intel Xeon "Nehalem" processors
6GB (6x1GB) of 1066MHz DDR3 ECC memory
640GB Serial ATA 3Gb/s 7200 rpm
18x SuperDrive (DVD±R DL/DVD±RW/CD-RW)
NVIDIA GeForce GT 120 with 512MB GDDR3 memory

this one has no wifi, smaller harddrive, weaker video card but I want the 8 core so i took out the tray at the bottom with the 8 core and put it in my 5,1 which had the 4 core and it booted up fine except all the fans started blowing full blast and got real loud I got kind of scared and turned it off.. I could also just probably swap the hd, video card and airport card over to the one with the 8 core but the 4 core case is nicer condition, anyway any help would be greatly appreciated and hope I didnt confuse anyone thanks

 

[Detrius]

I expect the fans went nuts simply because the firmware didn't know what to do with the temperature sensors, and Macs take the safe route in those cases, running the fans full speed. It's annoying, but it's safe.

The newer machine takes faster memory, but they both max out at 32GB of RAM. If what you're doing is memory intensive, the newer machine would be faster with the same amount of RAM. If it's CPU intensive, the older machine would likely be faster.

Also, you posted this in the iMac forum. You'd probably get a better response from Mac Pro owners.