Welcome to the MacNN Forums.

Cyogen · Feb 27, 2012, 02:31 AM

I just bought a new psu for my Mac pro 2006 but it said it was for a 2008. I just checked the voltage on the 2 top to 12 v rails on the 2008 it's 18 A. On my old one it's 13.6 is this going to fry my logic board. The reason I bought a psu is I broke the heatsink temp sensor and now my Mac turns on with the fans on full speed and nothing else happens.
Ps the green power led inside my Mac is not on when connected to power outlet.

I checked the diag led the trickle amber light comes on only.

That's why I bought a new psu thought it might have gone bad. I have not installed the new 2008 psu I bought from eBay so hope some one will know if the 2008 psu will work

Cyogen · Feb 27, 2012, 04:19 AM

Does any one have a clue what this means on the diag led when I push the diag button on the logic board only thing lights up is trickle ? In amber color Ps if the Mac pro is off and the power cord is plugged in isn't there supposed to be a green led light on ? On the logic board Just trying to see if it's the psu or the logic board ps when I hit the power button all case fans go full blast I get no chime or boot screen ???

cgc · Feb 28, 2012, 01:00 PM

Originally Posted by Cyogen

...I just checked the voltage on the 2 top to 12 v rails on the 2008 it's 18 A...

If you think your voltage on the "2 top to 12 v rails" are "18 A" you probably shouldn't attempt to do this PSU swap.

Specifically what did you check and how did you check it? What is your reference to know what it should be?

Waragainstsleep · Feb 28, 2012, 01:45 PM

The Mac Pro, Mac Pro 8x and Mac Pro Early 2008 all have different part numbers for their PSU. That doesn't mean they aren't compatible but only Apple can tell you that without trying and they won't. Tell you that is. I wouldn't risk it myself.

The trickle LED is supposed to be the only one that is on when the cable is plugged in, I thought I answered this for you in another thread. It looks to me like your PSU is fine since your fans come on. Now you've admitted to breaking the heat sink temp sensor it makes perfect sense. You need to fix or replace that sensor or your fans are just going to run full blast all the time because the Pro will think its overheating.

Does the machine actually boot up?

Cyogen · Feb 28, 2012, 04:15 PM

My Mac Pro does not boot up. It just turns on and the system fan starts out slow the runns @ %100 I did order a new heatsing oem one because on one of my heat sinks tem sensor wire broke. Thats what I was thinking to that the Logic Board has a failsafe and if it does not detect the heatsink sensor it will not boot machine and try to run the fans at full speed.

That being said if you have a heatsink temp sensor wire broken. mac pro wont boot ????

Waragainstsleep · Feb 28, 2012, 08:22 PM

No, the broken temp sensor will make the fans run fast but should not prevent booting. Something else is wrong too. You'd probably be best taking it to an Apple store since they will diagnose it for free.

Cyogen · Feb 28, 2012, 11:06 PM

I sure hope its not the logic Board.

Is there a way to test the logic board ? To see if anything is Wrong ?

reader50 · Feb 28, 2012, 11:14 PM

Does anything appear on the monitor when you try to power up?

Cyogen · Feb 28, 2012, 11:22 PM

Nothing Appears on the Monitor I remebered there was a Green LED light that came on inside the Logic Board When it was fine. No thing Comes on but the System fan at Full throttle and When I hit the Diag LED Button the only light that comes on is the Yellow Trickle light.

Cyogen · Feb 28, 2012, 11:26 PM

Does anyone have a Mac Pro If you do Can you Please open the Side and Just have the power plug pluged in and see if a Green LED Light Comes on inside the Tower on the logic Board. I am hoping its the PSU like maybe one of the 12V Rail thats gone bad