determine if i need service - cpu fan imac 11G63

hello

this imac was upgraded way back when i first bought it by OWC but is not in warranty. they installed SS Drives and upgraded RAM.

Never had issue until 2 days ago fan started running high. this is with just browsers, open office and other minor apps/use.

last night installed Macs Fan Control and set to Custom - it turned fan off but mac crashed few minutes later. Uninstalled Macs Fan Control and installed iStat menus.

with iStat can see it is CPU fan. this morning after mac was off all nioght started out no prob but within couple hours fan came on and fan speed weant from 900rpm to right now holding at 4196rpm

can see progressive stats in images

tried reset pram and swc already

Software Mac OS X Lion 10.7.5 (11G63)
Processor 3.4 GHz Intel Core i7
Memory 16 GB 1333 MHz DDR3
Graphics AMD Radeon HD 6970M 1024 MB
27-inch, Mid 2011

bobmane said:

with iStat can see it is CPU fan. this morning after mac was off all nioght started out no prob but within couple hours fan came on and fan speed weant from 900rpm to right now holding at 4196rpm

Click to expand...

Fan rpm in the images show about 1000rpm.

- Nick

maybe i misunderstand what is what but if you look midway in the 3 images you see cpu, hdd, odd. i am talking about hdd number.

Sorry. I now see that each of the images contains rpm info. I was looking at the image where all three rpm values are around 1000.

- Nick

Your CPU fan speed does show an increase from around 1000 RPM to 4000 RPM or so which indicates activity of some sort. Have you checked your activity monitor to see what's going on as the CPU fan speed increases? The temps haven't changed much simply because the fan is doing what it's supposed to be doing and that's keeping the CPU cool.

When was the last time you blew the dust out of it?

@ chscag - i unplugged all usb and tb connected and did full shut down for an hour. started up and was back at about 900. been using only firefox about 5-10 tabs after about 1.5 hours back up to 3500 and fan running. normally i ran pro apps high demand so it is strange that this is with only browser. mayby the fan always did that and i never noticed? not sure but i dont think it did.


@ cradom - i have never - all i have is a dyson. can i do it with that and no disassemble?

https://www.google.com/?gws_rd=ssl#q=how+to+blow+out+an+imac
One of the hits is from our very own forum...

posts i read indicate many folks only wipe vents (already done) and possibly blow canned air (which sounds like it would not do much??). no way i am opening it...would have to have it sent in.

so at this point I I did ---> restarting in Safe Mode to clear caches https://support.apple.com/en-us/HT201262 , then do a PRAM reset, SMC reset, PRAM reset, SMC reset

still same.

after shut down i unplugged all usb and tb connected devices and did full shut down for an hour.

here is breakdown of one hour just using firfox :

time rpm degrees
12:00 900 132
12:20 2228 140
12:29 3390 136
12:39 4200 128
1:00 4200 120

bobmane said:

so at this point I I did ---> restarting in Safe Mode to clear caches https://support.apple.com/en-us/HT201262 , then do a PRAM reset, SMC reset, PRAM reset, SMC reset

still same.

here is breakdown of one hour just using firfox :

time rpm degrees
12:00 900 132
12:20 2228 140
12:29 3390 136
12:39 4200 128
1:00 4200 120

Click to expand...

chscag earlier mentioned launching & looking at Activity Monitor. You need to look here when your temp. and rpm's increase. There may be some activities going on here that you're not aware of.

Look at the total CPU usage numbers…and look thru the activity list to see if something in particular is using a lot of CPU resources.

Sometimes (many times)…folks install apps. And may not always understand what the install of that app or apps. involves.

- Nick

i have had it open with cpu% selected and firefox is at top because its all i have open...below that are mostly system services.

bobmane said:

i have had it open with cpu% selected and firefox is at top because its all i have open...below that are mostly system services.

Click to expand...

Great to hear that you have Activity Monitor open. But without providing any values…we cannot determine if the CPU's numbers are normal/good/bad.

- Nick

what values in activity monitor are useful to post?

bobmane said:

what values in activity monitor are useful to post?

Click to expand...

CPU:

- % User
- % Idle
- % System

If…% System number shows a high number (a number probably higher than 10-15% if only having an internet browser open). Check the "All Process's" iist for anything using a lot of CPU resources.

- Nick

- % User 1-6%
- % Idle 95%
- % System 1-2%

nothing using high in list...Firefox uses 10-30% intermittent - no other programs going

after couple hours now holding at 120 degrees and 4200rpm with fan humming along

bobmane said:

- % User 1-6%
- % Idle 95%
- % System 1-2%

nothing using high in list...Firefox uses 10-30% intermittent - no other programs going

after couple hours now holding at 120 degrees and 4200rpm with fan humming along

Click to expand...

Those Activity Monitor numbers look fine.

If & when the computer temps increase to the level you are concerned about. Look at Activity Montor again...and see if anything is out of line.

- Nick

thanks....guess i should have started with the obvious. is it normal to have the fan run at sustained 4200 with just internet browsing?

bobmane said:

thanks....guess i should have started with the obvious. is it normal to have the fan run at sustained 4200 with just internet browsing?

Click to expand...

No, it's not normal. Neither of my iMacs have ever sped the fan up to a high rpm while just browsing. Now, if you're viewing or playing Flash games, then the CPU fan will definitely speed up. But just normal browsing, no.

bobmane said:

thanks....guess i should have started with the obvious. is it normal to have the fan run at sustained 4200 with just internet browsing?

Click to expand...

I was going to say the something as chscag. Normally no.

But doing things like online gaming, maybe watching videos…or…operating your computer in a hot room (or a combination of these) can make your computer run hotter.

And this of course assumes that the computer isn't dirty inside. Add a dirty computer + one or more of the above…and you can have a hot running computer.

- Nick

FWIW: I have a similar mid-2011 2.7GHz 27" iMac, now running Mavericks 10.9.5 and sometimes ran into higher temps than I wanted, and tried custom iStat Menu fan settings but it didn't alway work properly so I switched to using Macs Fan Control. It worked a bit better but the CPU temp would still often climb higher than I wanted, and often for no real reason I could find.

Then one day at the developers site, I noticed a comment about the heat sensor locations, and the fans and air flow. So I made a small change to the "ODD" setting based on the GPU Diode temp.

Instant improvement on the CPU temp and it still is.

My typical temps and settings with Macs Fan Control running and iStat Menus Sensors Off: