What version of ESXi to install on UCS B Chassis ?

Question

I am in the processing of bringing up a B chassis.  I found a copy of ESXi 5.0 that was "tweaked" by Cisco.  I have tried several license keys and they arent accepted.  I took the PAK keys as provided by Cisco and generated the VMware keys at the VMware link.  Should I be using ESXi 5.1 instead ?
Ron                  

Answer 1

Finally got the problem resolved on my own after several hours.
Here are the lessons learned to help others from avoiding this situation -
1) When you registered the PAC keys on the VMware licensing portal, you should receive an email from VMware giving the same information as what you had on the web page.  Part of the problem I ran into is that I never received the email, so it would appear that the license keys I had from the web page werent activated on VMware's end.
2)  The license keys are single CPU only.  The Vsphere client will not install a single CPU license on a B series blade because it is a dual cpu configuration.  The licenses are not additive, in that you cannot install 2 single CPU licenses in order to be properly licensed.  I had to go back to VMware's licensing portal and "combine" two licenses into one.  Once I did that I was able to get the license to install.
3) It will serve you well to document the licensing when you first get it, what licenses are combined to create the license that vSphere will accept and what serial number of the B or C series chassis that you are installing them on.  Dont see an initial need to do this but with the hassle I went through to get the license I had to a useable condition, this helps build an audit trail in case something goes south.
My concern is that the licensing group didnt appear to read the case notes that I entered.  From what I went through, this doesnt appear to be either documented or published to the point where it is easily found.  If there is interest, I will be happy to create a document listing the steps to go through to make it easier for others.