The original PSU was a Seasonic Super Silencer 400W, which is rated at 22A@12V, 30A@5V, and 28A@3.3V. I replaced it with a Seasonic S12 600W which is rated at 18A@12V1, 18A@12V2 (not used), 30A@5V, and 30A@3.3V.
One thing did occur to me that my HSF is a Scythe Ninja, which is one of those...