It should have a Thermal sensor I think it's the "SYSTIN" one. You can download Asus AISuite2 and that will give a reading of the Northbridge sensor.http://www.asus.com/Motherboards/Intel_Socket_1155/P8Z77V_LX/
I tried AISuite2, and that only gives me a reading for "motherboard" which is very vague.
I found another app called HWiNFO64 which does show me a temp for the PCH, and it's displaying 45C. I hope it's reading the right sensor here, because this is what I was looking for.
Are you 100% sure that SYSTIN is the PCH? Because if it is, then I've got two different apps reporting completely different temps.