My mac pro 2,1 logic board

according to your generation number (2,1), you have Apple Mac Pro 8 core 3.0 Ghz (4 core x2), 667 memory bus, Mid 2007

the 820-2129A is for 8 core machines, 1st generation version 2, will take 2 quad core processors, model on Mac pro should be A 1186

the 820-2128 B is for A 1186, MA 970LL/A from 2008

there is a way to check compatibility. It's the ANS code. look for a tag that has has 11 letters/numbers on it,. don't go by the serial number of your machine

you want the last 8, 9 and 10th letters/numbers from that tag. you can also find it by using the last 3 letters before the last digit of the serial number of your logic board (or backplane board as it is sometimes called)

so, for the 820-2128B the ANS code for this is XDA

for the 820-2129A, the ANS code would be X7Q

it's also called the EEE code)

I'd have to say, at a guess, not really. maybe the 820-2128B might have been from a different generation, either later or earlier. My advice to you would be to return the 820-2128B and see if you can get the 820-2129A mobo instead. It may fit, but I've never replaced one before. The cpus might work with it, but I've never done one of those either. I tried to do it with my phat ps3 and I messed that up, so I quit. I wouldn't take that chance, frankly

good luck

JB

Maybe-I think you mean 820-2129-A right? ... you're sure that your logic board is faulty? I believe you, but--swapping out a logic board, CPU's, power supply, etc is a huge job. If you're 100% certain- absolutely, but if you're not... make sure you know what you're doing before you try...

go here for a service manual

hopefully I won't get in trouble for posting this link

http://tim.id.au/laptops/apple/macpro/macpro.pdf

just my opinion

JB