Is this the part I would be replacing?
Yes ...but no!........I forgot about the heat-pipes to the mosfets......been a while since I pulled my board apart (Full Water) so we have to work with what we have......gently pry off the top blue cover...it's held down by a polymer glue so never really goes off completely.....this cover is not really necessary as it's a convection design feature and will inhibit direct fan flow ......this will be good for a few degrees alone.
Next question......when you read the system temp at 50/51C is that as soon as you boot-up or does it steadily climb to that figure?
Point two...... have/can you test with a third party software system monitor (temps) to get a comparison.....could be BIOS is reporting it incorrectly or a crook thermistor
P.S......I'm also wondering if they had this heat-pipe off and put it back on (R&R) with not enough care with new Good thermal pads and goop on the chip
Aussie Allan