[dojoboy]

I just set up my new iMac today, just arrived today. It's a 24" / 2.93GHz / ATI Radeon 4850.

I've noticed it is quite hot. The upper sides and top are hot, not warm. The lower sides and bottom are room temp. It sits on a table with plenty of open space around it. ??? Is this expected?

My other iMac, a 20" / 2.0 GHZ / ATI Radeon 1600 never did this. Of course, the hardware is significantly different.

I'm going to shut it down tonight, but I never turned off my othe iMac - unless I was away for several days.

Any thoughts?

[teflon]

grab istat pro and istat menus and sit and very anally watch the temps..

[dojoboy]

Got 'em. What is a normal range?

[The Liberator]

Dunno the normal range for the new aluminuim iMacs but my G5 runs at about 55˚ C (for the CPU) and the plastic is not really that warm the touch, let alone hot. Anyone else?

Liberator.

Edit: I changed the temp from 65 to 55, as the later is the more accurate idling temp, while the other is the more accurate work temp.

This post has been edited by The Liberator: 24 June 2009 - 03:28 PM

[Sneaky Snake]

I've heard that the normal range is 50-60 degrees celsius. I'd start getting concerned if the temperatures are in the high 70's or 80's. That's when damage can start to occur.

[dojoboy]

Hm, is the default measurement for istat celsius? If so, it's been measuring in the 40s and 50s after an hour or so. The machine is warm though, didn't seem as hot this morning.

[teflon]

Then its fine. My MBP idles at around 45C today. When it gets up to 60C I start to think about turning the fans up manually, using SMCFanControl. When its at 75C and up, I expect the fans to be very noticeable, and it generally levels out temp wise at around 82C.
Damage to the actual chips shouldnt happen for quite some time, since they are rated up to beyond 100C.

All my temps were from the CPU, whilst the GPU idles about 5-10C hotter and gets hotter much quicker.
With the HDD, they don't like to be above 40C too much, but mine idles at 33C. Lots of disk writing and/or the CPU and GPU kicking in has it going up to maybe 37C and very rarely beyond 40C anyway. Of course, thats a laptop drive, but its doing 7200rpm instead of 5400. For reference, the HDD that was originally in my MBP ran quite a bit hotter in general.

On the whole though, if you've got iStat menu running and the CPU is kicking about for no reason, have a look, kick out any frozen/unwanted processes and maybe turn the fans up a bit yourself. If Im setting the machine something big to do, then Ill turn the fans up before hand myself to give it a good headstart. But really dont worry about it much, its only when you're getting past 85C that you should be thinking "oh sh*t!", the rest of the time its just being cautious.

[dojoboy]

Cool, no pun intended. I'll d/l smcFanControl when I get home to be preventitive, maybe set up a couple profiles that I've seen others doing. Thanks, fellas.

[Sneaky Snake]

I wouldn't worry about your temps unless they go into the 70's C, and even then just start to keep an eye on them. If it hits 80's C you should probably start to crank the fans. 90+ C and you should probably stop what your doing.

[dojoboy]

Here's what I get after about an hour. Maybe my concern is derived from 3 years out from the latest and greatest.

iStat


Fans

[The Liberator]

How did you have so many readings? I only have the simple CPU, Sytem and HD readings for the fans and temps.

Liberator.

[dojoboy]

The Liberator, on June 25th 2009, 03:27 AM, said:

How did you have so many readings? I only have the simple CPU, Sytem and HD readings for the fans and temps.

Liberator.

iStat or smcFanControl?

[teflon]

He's probably got more sensors than you Liberator. In comparison to G5s its going to be a few more sensors (some of which just duplicate one another), but your C2D iMac should have about the same.

Personally, I say that all looks fine for the most part. The fans are running nice and low, the CPU is cool, the GPU is right where mine is (the diode a bit lower, the heatsink a bit higher, so it evens out).

My only worries are that the Northbridge is at 70C whilst idling, but since I dont have a Northbridge temp in my MBP I cant compare. But more worryingly than that the HDD is at 48C. Generally they're quite happy in the high 34-42C. Above that point you see a lot more HDD failures.
Of course, if you were doing a lot of heavy lifting on your HDD (but not taxing the CPU/GPU much), then that could explain the temp there. So just keep an eye on it and make sure you've got a Time Machine backup and/or a CCC backup made weekly.

do you still have the old iMac? would be good to compare the temps you're getting.

[The Liberator]

teflon, on June 25th 2009, 10:02 PM, said:

He's probably got more sensors than you Liberator. In comparison to G5s its going to be a few more sensors (some of which just duplicate one another), but your C2D iMac should have about the same…

Ahhh, okay thanks. I thought as much.

By the way, what is a Northbridge?

Liberator.

[teflon]

The Northbridge and Southbrige control the access to all the various inputs and outputs and components etc. etc. etc. BTW, its analogy time so here goes.

If you think of your computer as the Roman Empire, then the CPU is Rome. The Northbridge sits between Rome and the rest of the Empire, and everything has to go through it to get to the Senate. Primarily it handles communication with the RAM (Italy), these days, but used to also get in touch with the AGP GPUs. More recently the Northbridge has been integrated into the CPU's die, effectively making it the walls of Rome.
It also has to be gone through to get to the Southbridge (the rest of the Empire), which is the gateway to the optical drive (Britain), USB and other ports (Spain), HDD (Germany), PCIe (France), Power (Greece), Fan control and temp monitors (Northern Africa & Egypt).

So there you have it. Its just an IO controller. But its obviously going to have every single piece of data that the CPU gets going through it, so needs to have one heck of a big bandwidth to accommodate all this stuff. Its also always going to be working.

[dojoboy]

teflon, on June 25th 2009, 08:02 AM, said:

He's probably got more sensors than you Liberator. In comparison to G5s its going to be a few more sensors (some of which just duplicate one another), but your C2D iMac should have about the same.

Personally, I say that all looks fine for the most part. The fans are running nice and low, the CPU is cool, the GPU is right where mine is (the diode a bit lower, the heatsink a bit higher, so it evens out).

My only worries are that the Northbridge is at 70C whilst idling, but since I dont have a Northbridge temp in my MBP I cant compare. But more worryingly than that the HDD is at 48C. Generally they're quite happy in the high 34-42C. Above that point you see a lot more HDD failures.
Of course, if you were doing a lot of heavy lifting on your HDD (but not taxing the CPU/GPU much), then that could explain the temp there. So just keep an eye on it and make sure you've got a Time Machine backup and/or a CCC backup made weekly.

do you still have the old iMac? would be good to compare the temps you're getting.

Which fan should I bump for the Northbridge?

I do have the old iMac and can take a look.

Initially, I did do a good deal of file transfers. Don't know if that would heat things up for the HD. Is it safe to assume the Northbridge should be hotter than the CPU?

[Sneaky Snake]

teflon, on June 25th 2009, 10:49 AM, said:

The Northbridge and Southbrige control the access to all the various inputs and outputs and components etc. etc. etc. BTW, its analogy time so here goes.

If you think of your computer as the Roman Empire, then the CPU is Rome. The Northbridge sits between Rome and the rest of the Empire, and everything has to go through it to get to the Senate. Primarily it handles communication with the RAM (Italy), these days, but used to also get in touch with the AGP GPUs. More recently the Northbridge has been integrated into the CPU's die, effectively making it the walls of Rome.
It also has to be gone through to get to the Southbridge (the rest of the Empire), which is the gateway to the optical drive (Britain), USB and other ports (Spain), HDD (Germany), PCIe (France), Power (Greece), Fan control and temp monitors (Northern Africa & Egypt).

So there you have it. Its just an IO controller. But its obviously going to have every single piece of data that the CPU gets going through it, so needs to have one heck of a big bandwidth to accommodate all this stuff. Its also always going to be working.

+1 for that analogy

[teflon]

I thought it was another good one. Not to mention that Frost should enjoy it, and everyone knows you need to pander to the dictators so you can get close enough to slip poison in their tankard of ale or just go with a good 'ole fashioned knife to the kidney/heart.

As for the fans, looking at the 20" iMac I cant really point out the Northbridge on the motherboard, so cant see which fan should be turned up. But I wouldn't really worry about the Northbridge, since its rated to much higher temps and on 99% of motherboards just has a heatsink slapped on it, relying on the air being pushed around by other fans to cool it. Having said that, yes, they do tend to run hotter than CPUs do, but I havent found any solid guidance in my brief google search.

What I'd be cautious about is the HDD, which, though it has its own fan, and all the other components are pushing their heat to either side with heat pipes, could still get a decent amount of heat passed onto it. Though it could just be residual heat from previous work, since HDDs take a while longer to cool down in my experience.

As I said before, Id monitor those temps for a while and get a feel for where they tend to be under what conditions. Don't panic about it, just be watchful. Then after a week or so of putting the machine through its paces, you might want to create a few SMC profiles to get ahead of any heavy work load, not that it should be necessary, Apple have obviously worked the machine to be within certain tolerances and 99.5% of the time the machine will be fine without any fiddling.

[The Liberator]

Okay, thanks Teflon. Good analogy also.

Liberator.

[dojoboy]

I bumped the fans 200 rpm each and set as a profile. I'm feeling much better about it regardless.