The numbers certainly look better with hwinfo. Thanks for the tool!
I've seen Intel's BIOS screen reporting temps of ~400C on an unrelated motherboard before so I wasn't sure if this was GPU-Z or Intel's sensors being wonky.
Can someone with the D54250WYK verify that GPU-Z v0.7.5 reports the wrong numbers? I want to make sure it's a general problem and not just my system.