Really odd problem with WD2002FAEX in MacPro 5,1 mid 2010

Question

Hi all,
Please help.
Current configuration:
Mac Pro 5,1 mid 2010
16GB (4X4GB) memory
Both optical drive bays loaded one Superdrive, one LG Blu-ray burner
One external NewerTech Guardian MAXimus connected FW800
All 4 internal drive bays filled with Western Digital 2TB WD20EARS
Bay 1 - boot
Bay 2 - time machine backup
Bay 3 - itunes
Bay 4 - time machine backup
Problem: initially interested in replacing iTunes drive and boot drive. SATA II drives look to be going the way of the dinosaur. They are starting to get a bit hard to find. Every site seems to state the SATA III drives are backward compatible to SATA II. ok. Here's the problem: When I swap the drive in Bay 3 with the new WD2002FAEX drive, on spin-up I lose my USB ports and Airport card. All communication stops. Thinking it was the drive, I returned it to Newegg. Purchased same drive at OWC. Installed drive, same result. Thinking it was Bay 3, I used another. Same result. Thinking it was the model of drive, I purchased a Seagate Barracuda ST3000DM001. Put drive in Bay 3, same problem. I retained the original drive that came with Mac Pro, Western Digital Caviar Black WD1001FALS, put it in, works OK. I'm thinking it's SATA III, but I've searched all over, and I can't find anyone else who has had this problem. Each time I take the SATA III drives out, my USB ports and Airport card return to normal like nothing happened. Also, when I have the SATA III drives in, it seems to take longer to boot up.
Any ideas?

Answer 1

I have found tones of documentation that stays that it indeed compatible, so...
So ignore the Apple support people.
They make loads of mistakes regarding compatibility and are likely the last people that you should ask.
Also, when Apple discontinues a product, or, release a new product, they don't always list compatibility of older parts with newer machines. Also, they don't test the parts, so they don't say that the parts are compatible with new machines.
Users know best..... so does Nvidia. Under Drivers and Downloads:
Mac Pro Requirements: >>To find out if you are running the correct Mac Pro, go to About This Mac to find out what system you are running. You can find this by doing the following:
Go to • About This Mac
Click on the • More Info button
Select • Hardware
The model identifier should be MacPro3,1 or MacPro4,1 (2008 or 2009) or later
Note: MacPro1,1 and MacPro2,1 are not compatible.
http://www.nvidia.com/object/product_quadro_fx_4800_for_mac_us.html
That would make the MacPro 5,1 compatible with the Quadro 4800 FX......
Ignore Apple support.