Probably a little late for a reply, but I have 2 thoughts.
1. Running unsupported hardware in your server I would think would be justification enough to shut it down to replace. Doesn’t matter if it works or not.
2. If not, then my other thought is this. If you have a hardware maintenance contract with IBM(or anyone else for that matter), and you have need for a service call, you can bet that if the technician sees you are using unsupported hardware he will point at that as the cause, and also bill you for the call.
If your server is so important that you need justification to shut it down to put the proper hardware into it, why would you run the unsupported hardware in the first place?