Buying a used 2009 Mac Pro

[666sheep]

What do you guys think about this RAM

http://www.ebay.com/itm/16GB-8X2GB-...4332277?pt=US_Memory_RAM_&hash=item43afecac75

Is it compatible with Mac?

As xcodesyn said it isn't compatible. Only dual rank (2R) is.

But it isn't true that 667 MHz RAM is too slow for 2008. Many people just uses it in 3,1 because it's cheaper than 800 MHz one and only insignificantly slower (200-300 geekbench points max). For about $200 you can get 32GB of 2Rx4 667 MHz compatible RAM.
If you want to run couple of VMs, it's better to have more RAM than faster RAM.

 

[cyber16]

update
A local Craigslist buyer received a great deal on my pro, sounds like they will be able to use its capabilities.