Mac Pro experts, I have system sensor error

When running the AHT test, my Mac is showing an error.
I've decoded the error, and it tells me the culprit is the system sensor for temperature in the memory/memory riser boards.

Anyone have an idea where these are?

I heard there's such sensors in RAM sticks, should I perhaps just swap them? I don't have any other RAM to test here at the moment.

That's what I assumed. Let's say it was really the case that the sensors on the modules are damaged, would I still be able to start the mac, or would it tell me the ram is faulty? Because I can start and use it without problems.

666sheep said:

Any particular reason you needed to run AHT?
Did you encounter some problems with your MP?

Regarding temp sensor: if you see its reading in iStat (or similar) and it isn't extremely high or low (comparing to other modules), then you don't have to worry.

Click to expand...

I bought the Mac and first thing I did was run the test to make sure it's all okay. Since it shows an error, it isn't. Else I believe it runs normally. It's a bit loud sometimes, not because of the video card fans, but because of other fans. Probably because the temperature sensors are not working, it runs the fans faster than it should.
Also I heard artefacts through the audio output but that's a different and probably unrelated story.

It was built in late January 2011 in Ireland so I guess it's a 5,1? Yes it's the one in my signature.

I'll test the fans later, and I have a 7950 Mac Edition, but that's not the problem, because I hear some fans running, but there's no air coming out of the PCIe bay, so it isn't from the card. But perhaps it's normal, I was just used to computers that are more quiet before. I'll still check out the fans.

I believe it's the RAM, but it might be the slots too. I did following tests. I have 2 x 16 GB in the Mac, I removed one of the bars, leaving only 16 GB. I ran the AHT only with this bar, then with the other. The same result came out. My error started with 4SNS, which states a sensor error. Then came TMA1. T stands for temperature, M for Memory OR Memory riser boards. After having switched the RAM bars, changed the slots, ran the AHT again and so on and so on, I figured what the rest means. "A" stands for the side of the RAM Bay. There's 4 slots at the front, 4 at the back. "A" are the front RAM slots (where the door is), "B" would be the one at the back. The number after that letter stands for the slot itself, but it only goes up to 4, not 8 as marked inside the MP. Instead, if slot 6 is meant, it will show up as B2 for example.

So while experimenting, I got all kinds of results - TMA2, TMB1, TMB3, etc. - basically, wherever I moved the RAM, it would show this error. Pretty sure it's the same therefore. It's sad because I sent the Mac back to Germany and the seller changed the whole logic board apparently. I haven't tested all of the RAM slots, but one (which was number 4 at the back) wouldn't let me start the Mac. The light was blinking, apparently it means faulty RAM or something.