There is absolutely no way that happened. 15 years ago, we're talking Fermi class GPUs and chips with hundreds of millions of bits of on-chip state and much more if you include the DRAM.

You can't tease out the right information by applying random inputs. Which input would you even use? The PCIe interface? You'd first "randomly" need to get past its complex training sequences...

Your postdoc probably wrote micro-benchmarks of some sort. That is a common technique.

And you don't use an o-scope in anycase, since you'd need...what...a thousand of them to watch all the signals. You'd use a logic analyzer. I think I read somewhere that those older nvidia chips had something like 2000 BGA balls, and Tektronix does make an LA that can scale to 2000-something channels (TLA7000), for a modest US$500k or so. Then you gotta figure how to mount the thing to attach the probes.

So...agreed...far more likely there was a software solution of some kind if this happened.