Nah, HDD cant possibly affect BIOS post message in any sort of way, it will only stop when it finds a faulty HDD, not mess with display of it.
As Evildeffy said:
Its probably your GPU, apart from the obvious artifacts i have seen it before with my GPU and a friends.
The card isnt dead yet, but its VRAM is near death hence you are getting that.
It works during benchmarking cause you force it, and crashes randomly after that, my GTX 580 did the exact same thing since i noticed it was dying, i benckmarked it multiple times and no problem, only for it to die completely 2 days after with artifacts and black screens also and then artifacts at BIOS and dead.