Q: New iMac 27inch screen flickering/tearing/shutoff

uh no...how is his statement political?

Re: swimmerjf

"Everyone is talking about their machines being week #, etc. (i.e., week 47). I would appreciate it if someone would tell me what that means and where that information is found."

It refers to the week when the machine was manufactured. You can find out exactly by putting your serial number in...

http://www.chipmunk.nl/klantenservice/applemodel.html

C'mon man, don't be an a$$hole. I can guarantee that those credentials are authentic, and I think my employer feels I'm quite worthy. Besides, you started with the "lubricant viscosity" nonsense.>

I don't care about your credentials pal (authentic or orherwise) but I do take exception when you try to use such - to apply undue leverage in debate, rather than use the facts at hand and everyday common knowledge.

Of course ambient temperatures significantly affect the computer's internal component temperatures which thereby affect target and actual fan speeds. I'm not arguing that point.>

Yes you were.... but, I'm over it now and got past it satisfactorily.

What I am saying is that it appears, at least in my case, that the +absolute minimum possible fan speeds+ are set by the firmware...an assertion borne out by the Fan Control preference pane. According to the temp vs. RPM graph, I could take my iMac to the South Pole, run it outside, and the minimum fan speeds will never drop below 1200/1200/1000 RPM. Based on the screen shot of the preference pane I posted above, how can you draw any other conclusion?>

Fan speed is controlled by regulating voltage to the fan motor. That being the case, it is not an absolute method for fan speed control - but rather a function of a Regulators capacity to make change and to its accuracy & calibration.
Your Fan control utility and associated preferences indicate the parameters to what it (by itself) is able to alter - in the control of fan speed.

Honestly, I think we're talking past one another, so we probably should just give up. I'm willing to concede the point -- the conclusions I've drawn were based solely on the apparent functionality of that preference pane, not any underlying physics.>

Good for you..... I'm glad you are big enough to concede that (my only real point)

Oh yeah, thanks for taking a personal shot at me though, I appreciate it.>

You are welcome.... if the cap fits - wear it !

Hi Peter,
Thank you for this link.... the information it generates - is very useful

EG; it shows that the 24" iMac (C2D) I'm using now... was made in China (I knew that) but
it also advises- this machine was configured in Czech Republic

Than you again...

NULCGI wrote:

Of course ambient temperatures significantly affect the computer's internal component temperatures which thereby affect target and actual fan speeds. I'm not arguing that point.>

Yes you were.... but, I'm over it now and got past it satisfactorily.

Please don't tell me what I was trying to say. I know perfectly well what I was trying to say...and you're still missing my point. Plus, I know how fan speed controls, regulators, etc. work. That's beside the point. I will try one last time.

On my system, the OS and/or software does not appear to be able to change the +minimum possible fan speed+ in response to system or ambient temperature changes. The OS/software absolutely can vary the fan speed as a function of temperature, just not below a minimum threshold value. The minimum possible fan speed appears to be fixed in firmware. So, on my system, the fan speeds will never drop below 1200/1200/1000 RPM, regardless if I'm running my computer in Antarctica or in the Mohave Desert. The only reason I mentioned this was because I was surprised that other folks were reporting speeds in the 900-1000 range -- according to the software installed on my system, my fan speeds simply cannot go that low, regardless of temperature.

I'm not trying to be an internet nutswinger by posting my credentials. I know no one gives two ***** about them. I only posted them to illustrate that your attempt to dazzle me with language like "lubricant viscosity" and "bearing friction values" wasn't going to faze me since I actually know what that means.

+Schwa72 wrote:+

I'm not trying to be an internet nutswinger by posting my credentials. I know no one gives two ***** about them.>

You are not wrong - there !!

I only posted them to illustrate that your attempt to dazzle me with language like "lubricant viscosity" and "bearing friction values" wasn't going to faze me since I actually know what that means.>

Hmmm.... You do have some sort of fixation on these everyday terms.... I mean;
1. Anyone who owns and services their own car.... knows what 'lubricant viscosity' is - and would use that knowledge when buying appropriate Engine Oil for there needs etc....
2. Bearing Friction value is equally a common term... that even Blind Freddy would understand.

Your assertion that I was trying to bamboozle you (or anyone) through use of these very common terms - is profound... quite mistaken and completely out of order. Furthermore, your continued reference to this - says much more about you (and your personal hang-ups) than it does about me.

I have little more to say on this matter, so lets move along - eh?

NULCGI wrote:
Hmmm.... You do have some sort of fixation on these everyday terms.... I mean;
1. Anyone who owns and services their own car.... knows what 'lubricant viscosity' is - and would use that knowledge when buying appropriate Engine Oil for there needs etc....
2. Bearing Friction value is equally a common term... that even Blind Freddy would understand.

We could argue about whether these are "everyday terms" until we're blue in the face (I know I don't stand around at parties talking about "lubricant viscosity" and "bearing friction"), but since they have no bearing (so to speak) whatsoever on the conversation at hand, I can't figure out why you would've mentioned 'em.

NULCGI wrote:

Your assertion that I was trying to bamboozle you (or anyone) through use of these very common terms - is profound... quite mistaken and completely out of order. Furthermore, your continued reference to this - says much more about you (and your personal hang-ups) than it does about me.

As does your statement: "Dunno which lucky bag you got those alleged credentials out of.... but if by chance authentic... you surely weren't there or listening - during the important stuff."

I have little more to say on this matter, so lets move along - eh?

Agreed. I'm done.

I so wish Apple would sort this problem out....the longer it goes on the more it damages its rep.

This is my first Apple computer and I have made the switch from windows at long last...so far so good but I can't help wondering if all new iMacs are ticking time bombs(not literally - i mean in relation to the flicker and blackouts)

Apple need to make some sort of statement to its customers perhaps... I don't know.... some guarantee to replace/repair if the computer develops a flicker or blackout any time within the first three years regardless of Apple Care....just like Microsoft did with their XBOX360?

Anyway will keep reading the interesting posts on this topic...oh and my fans are running at 997/1098/940 and never fluctuate much above that.....

Schwa72............Maybe I've missed your point.

If you are asking how so many others are posting fan speeds below 1200, while yours shows a minimum speed of 1200, they simply do not have "Fan Control" installed.

I use iStat to monitor temperatures without altering the parameters designed by Apple.

"Fan Control" resets those parameters, raises the minimum speeds, and allows you to adjust the speeds.

I do not recall a single occasion when my fans have ever reached 1200 even during heavy use, and all temps have remained within normal parameters, such as they are.

pazuita, thanks for the reply. The thing is that regardless of whether I have Fan Control installed, my fan speeds are the same (1200-1400 RPM range). They also vary appreciably depending on what the computer's doing; for example, when I'm doing a Handbrake encode, the CPU fan speed easily goes into the 1700 RPM-range. Because the actual fan speed behavior didn't change once I installed Fan Control, I assumed that the program was merely reporting the minimum fan speeds as established in the firmware, not that it actually modified them.

I suppose it's possible that my ambient temps are sufficiently higher than everyone else's such that my minimum fan speeds are higher, but that seems unlikely.

As I said, my previous Core i7 had exactly the same fan speeds as does my current machine, so in all likelihood the computer is operating properly. I just don't understand the different in minimum fan speeds, but it doesn't really matter that much to me.

im doing a handbrake encode as we speak and my cpu fan is at 1749 rpm with temp of 58c

Rather than the CPU - I would be more interested in the GPU temp and GPU diode temp ?

pazuita, just for ***** and giggles, I uninstalled the Fan Control preference pane, reset my iMac's NVRAM and SMC, and restarted the computer. By all rights this should've reset the minimum fan speeds to the firmware defaults. Anyway, when I restarted my machine and checked iStat, my fans were running at the same speeds they always have (see below). Oh well, no worries, there's certainly nothing wrong with the fans running a little faster than what you guys are reporting -- nothing wrong with keeping things cool, and at least they're not going completely apeshit!

63 and 62 respectively fan at 1180rpm

Knowing the week of production of your iMac is all well and good. But does knowing this number (week 49 for example) pinpoint anything? Is it reliable?
Whos to say that panels, motherboards, etc. is not lying around and the serialnumber is only assigned when the machine, as a whole, is assembled? This would mean, that a panel, produced in week 46 could go in a machine with a week 48 motherboard for example.
Someone with knowledge in this area, please enlighten us (me).