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Tucom

Cancelled
Original poster
Jul 29, 2006
1,252
310
When I reboot my Mac Pro or cold boot it after it's been turned off but NOT unplugged, then it does the turbine fan "woosh" and wirrs the fans until the Yosemite boot bar is half way done then everything quiets down.

It doesn't do this when it's been unplugged and then cold booted for the first time after being plugged back in. It bongs and everything, just the fans stay near silent the whole time after the power button is pressed.

Is this normal?
 

Tucom

Cancelled
Original poster
Jul 29, 2006
1,252
310
97 thread clicks and no one has any idea...?
 
Last edited:

Tucom

Cancelled
Original poster
Jul 29, 2006
1,252
310
Less than 12 hours is an unreasonable amount of time to bump your own thread twice, I'd suggest against that if you don't wish to be banned from the forum, be patient, somebody will provide help soon enough.

It wasn't an initial intention to have the thread bumped, meant to just add like an edit, but fair enough, I guess I got a little impatient.

On topic, does anyone have any idea about this? It's probably nothing, but one of those things that's kind of curious.
 

Silly John Fatty

macrumors 68000
Nov 6, 2012
1,745
460
I'm not sure if I understand what you are describing. Are you saying that, when you start your Mac, the fans are louder, and once the desktop appears, the fans go quiet?

If yes, then I believe that's normal. At least mine is doing this too.
 

Tucom

Cancelled
Original poster
Jul 29, 2006
1,252
310
sounds like my AMD graphics card. this is normal...

That is the normal part - that's what I'm saying, it doesn't do that when shut down, unplugged, and then plugged back in and powered back on.

Most likely fine, but still curious.

----------

I'm not sure if I understand what you are describing. Are you saying that, when you start your Mac, the fans are louder, and once the desktop appears, the fans go quiet?

If yes, then I believe that's normal. At least mine is doing this too.

I may have worded it confusingly, sorry - as I just said in my most recent post - that it does not do that when cold booted after being unplugged. All fans are silent. Then if I were to restart it via software then the fans go full bore etc. momentarily. Just odd.
 

Tucom

Cancelled
Original poster
Jul 29, 2006
1,252
310
I'll test it out when mine is plugged off then, I'm curious!

What graphic card do you have?

That'd be great! Currently using the stock Radeon HD 5770. The machine has been babied (AFAIK) with it's previous owner. The guy even had the receipt, original box, and everything else. So I bet the machine itself is fine - just kind of curious now. I was more seriously concerned earlier.

I think it may have something to do with the SMC and the way it resets when unplugged for 15 seconds (SMC or PRAM, though I think PRAM reset is done via command keys)
 

Silly John Fatty

macrumors 68000
Nov 6, 2012
1,745
460
Haha I know what you mean, when I got mine it was the same. Weird, unknown noises that worried me, and things like this, a bit like when you're staying overnight in a house you don't know :D
 

RoastingPig

macrumors 68000
Jul 23, 2012
1,606
70
SoCal
i have had many 4.1 5.1 mac pros...some do this and some don't...its perfectly normal with the 4870-5770-5870
 

Tucom

Cancelled
Original poster
Jul 29, 2006
1,252
310
i have had many 4.1 5.1 mac pros...some do this and some don't...its perfectly normal with the 4870-5770-5870

Interesting. Because mine does both - on cold boot for the first time after being unplugged it doesn't spin up the fans at all.

If I restart it then the fans exhibit the usual behavior.
 

Tucom

Cancelled
Original poster
Jul 29, 2006
1,252
310
Haha I know what you mean, when I got mine it was the same. Weird, unknown noises that worried me, and things like this, a bit like when you're staying overnight in a house you don't know :D

Did you ever get around to trying it out? I'm still curious :p
 

IowaLynn

macrumors 68020
Feb 22, 2015
2,145
588
Interesting. Because mine does both - on cold boot for the first time after being unplugged it doesn't spin up the fans at all.

If I restart it then the fans exhibit the usual behavior.

Use a good program to monitor the thermal sensor readings. Sometimes SMC can tell the temp, other times if it can't it still might kick the fans in to "blow any heat out."

My 8800GT was known for its fans to come on at startup (did not seem to matter or change between cold boot or not). My 5770 stays quiet.

To really reset the SMC, unplugging alone I have never seen to actually do anything, but pressing power button in for 10 seconds while everything was unplugged and no juice or keyboard, would. (and mine is shutdown, unplugged totally even for weeks and no it does not show the motherboard or SMC being reset.

There may be various models too of the "same" graphic card, chipset, GPU firmware differences, so those and other items can help too.
 
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