This question gets asked about once a week it seems.
It just started? not when you first upgraded to Lion?
Best way to upgrade to Lion is a clean install on another hard drive, then use Setup Assistant, and not upgrade in place over your old Snow Leopard system, and which may be still carrying around a number of incompatible 3rd party drivers, apps and background routines.
But you should definitely run AHT off your OEM DVD it came with.
Considering you have some 7 yr old FBDIMM I would not continue using those.
The OEM 7300GT is due for update to 5770 esp with 10.7.5
I just did those updates on mine and only months ago when I upgraded to 10.7.5 also.
There is an SMC Reset button on the logicboard.
Faulty readings from sensors?
ATI Radeon 5770
How To Install and Remove Memory Mac Pro2x2GB FBDIMM DDR2 667MHz @ $32
Sorry for raising this issue again.
I did a clean install of lion on a new HD.
The FB-DIMM modules is brand new ..
I reseted SMC pressing the button on the motherboard, the Mac Pro now works normally for 3 or 4 hours, after this time the temperatures of the heat sink go to 128 º C and the fans shoot.
only the sensors of heat sinks are to misreading.
note: during the period that the Mac works as usual, all sensors show the correct temperature.
I bought the ATI Radeon 5770 and I'm hoping the mail delivery.
I no longer have the DVD that came with my Mac Pro, but I downloaded the AHT on the Apple website and I will do the tests tonight.
Thank you for your attention!
Victor Tavares Ibrahim.