can utilising the cpu fully (400% for dual-core hyper-threading cpu) damage mbp I have recently bought a rMBP with i7 4578U intel 4th generation cpu. iStat usually shows cpu temperature readings of ~50 degrees which is normal.

Today, because of a buggy library code, my cpu had to run at 400% for 10mins or so before I have realised it was a bug causing this. The fan was pretty loud and iStat showed 99 degrees. However, as soon as I've terminated the process hogging the cpu, it went down to 80s in a second which means iStat readings might be inaccurate..

So, my question is, might this have damaged my computer somehow?

Thanks in advance.
Your Mac and Intel CPU have means of protecting them self from self destruction.

You Mac has thermal senors (same one that the istat uses) to monitor temperature and do something about it.

The Intel CPU has also a build in circuit to shut down before any damage is done due to overload or heat.

So no, no damage has been done in that short period.

However, running at elevate temperatures for extended time (days) will eventually reduce the life time of the CPU, by creating junction leakages and interconnect issues, that is why there is a build in circuit (inside the CPU) to stop that.

Credentials: I am a CPU design engineer.

PS

You Mac does not need iStat, that one is only for you to feel better, or not.