Different Windows editions support different amounts of RAM, for example:
Windows Server 2008 R2 Standard: 32GB
Windows Server 2008 R2 Enterprise: 2TB
I'm curious about the impact, if any, of having more than 32GB of RAM on a Server 2008 R2 Standard box. Will performance suffer due to Windows having to manage more memory, despite not being able to utilise it?
This question assumes that no physical or architecture limits are being hit. I.e., Windows is well aware that the machine has >32GB RAM, but only 32GB is usable.
No, it will not affect performance. It only maps the amount of RAM that the particular edition supports, that's all.
On modern hardware it will not affect performance at all.
There are exceptions, such as in the Pentium 1 era where some chipsets could not cache memory above 64MB (yes, megabyte, not gigabyte). I think it is safe to assume that you are running server 2008 on more modern hardware though. :)