That depends on whether you want to use this system-wide JDK with PowerCenter.
The clients are installed with their own JDK; for 9.1 it was a 1.6 JDK (I don't recall the exact version, and that's irrelevant here anyway). As long as the PowerCenter clients can use their own JDK, everything works fine.
Trying to use a different JDK with the PowerCenter clients may have all sorts of adverse effects, the best (no joke!) being that the clients simply won't start any more. In the end you could corrupt your repository beyond repair when exchanging the underlying JDK (that surely would be worse than the clients not starting, right?)
You can switch to whatever JDK you want on your Windows machine. Just make sure that the JDK installed with the PowerCenter clients is not touched in any way.
Informatica has its own java inside the informatica installation folder. If your java_home is pointing to this and the java upgrade that you are doing is not impacting the java version inside informatica installation folder, you should be good.
Thanks Nico for you information!
Thanks Thiyagi for your information!