Where is the SMC Chip?

The machine is booting up but the fan keeps cranking up to full power and very slow.

@notveryexperien This is actually pretty typical behavior when a Mac is not getting data, or is getting data outside an acceptable range from a a sensor somewhere. The Mac Pro has a LOT of sensors and ultimately they all talk to the SMC. Hence the reason why it flags that as an error. This could be any number of components. If you want a WHOLE lot of data, you can parse through Apple's Service Manual (2013 MP Repair Manual) for this. I would be especially interested about the "Computer Runs Hot" section which starts on page 129. Running things like AST (Apple Service Toolkit) are not possible as a normal user of these devices in my recollection. But there are a lot of parts in one of these Mac pros and there are sensors on a lot of them, this might help regardless of its "Apple speak."

Sorry for the late comment, does it mean I have to change the logic board? Or a gpu? Also, in the manual it says i do smc reset but still the fan keeps cranking up.

@notveryexperien It depends on which sensor is causing the issue. It could be bunch of different things. They do not always make it easy to determine which sensor is causing your issue without use of Apple’s internal diagnostic suite.

I might recommend downloading TG Pro to see it can shed some light. It won’t tell you about specific sensor issues with the free version, but we may be able to glean info from the information there anyway. Post a screenshot of your results in your original answer.

Well I decided to use Windows instead but PSU Secondary Heatsink and PCH Switch Diode shows no readout, Maybe it could be dead.