MacPro4 supports just one CPU following the X5690 upgrade.
MacPro4 supports just one CPU following the X5690 upgrade.
Recently I purchased new CPUs for my MacPro, installed them, but only one is functioning properly. One of the CPU cooling fins remains cool. Feel free to ask if you need more details!
Swap the CPUs and check performance. If the cooler socket heats up while the other stays cool, the second CPU might be damaged and needs replacement. If both work normally, the issue likely lies with the second socket.