iMac problems, need advice.

[Haleth]

Hey all.

So a few months ago I've bought my new iMac, the one I asked for advice on in a previous topic. I'm here to ask advice once again!

First, the specs:

27", 2560 x 1440
Intel Core i7 "Sandy Bridge" Quad-core 3.4 GHz
4GB 1333MHz DDR3 SDRAM
250GB SSD
AMD Radeon HD 6970M with 1GB VRAM

At first it ran WoW like I expected it to, usually no lower than 60 fps and maxing out well over 250 (locked it at 60 with vsync) on full ultra apart from shadows. The only thing it struggled a little on was high particle density effects, a known issue in Lion apparently. The GPU temps were a bit hot in my eyes, they ran up to 87°C (188.6°F), but people smarter than me confirmed that those were perfectly normal. Other temps were nice and cool.

What I did notice is some Lion-specific issue where games could get stuck at a lower frame rate (weaker GPU performance) after having played any type of video content. I've reported this to Apple Developer Bug Report and they confirmed the issue. Luckily with my SSD, reboots are extremely fast (<10 sec) so that wasn't too much of a problem.

In the past few weeks though, something strange has been happening. The card has started to run extremely hot, heating up to 94+°C (201.2°F) in no time when playing games. However, there is no increased fan activity with the ODD fan (also responsible for cooling the GPU) running at its minimum RPM of 1150. As the GPU hits 98°C (208.4°F), whichever game I'm playing starts stuttering, and at exactly the same moment the ODD fan revs up to about 1800RPM. This lasts for about 10 seconds until the card has cooled down, then the stuttering stops and the fan reverts to its minimum value. After a few minutes, it happens again. The other components are still equally cool.

This will always happen at one point, but it's almost instantly triggered by things that are heavy on the GPU such as the high particle density I mentioned earlier. Zooming in on a graphical effect is almost like pressing a button that says "overheat".

I've done all the usual stuff; reset SMC, reset PRAM, reinstalled Lion (two freaking times). My computer shipped with Lion so I can't downgrade to Snow Leopard to see if it changes anything. My computer appears to be weirdly incapable of accessing the Apple Hardware Test even when connected to the internet while trying to run it (it had Lion preinstalled, so it needs to download these tests first). I can't check if my hardware is faulty because of this.

I've called AppleCare which just resulted in me being pissed off at the terrible customer service (I'll spare you the details), then instead started mailing my local store which went a little better. One of them told me that the temperatures are still 'within operating values' seeing as the GPU can handle 105°C (221°F). After I told them that the stuttering is far from normal and my previous iMac never did such things, they suggested me to bring it in to the store.

This is the problem; it's a 27" screen, it's quite a drive to the store and there are roadworks everywhere, so I -really- don't want to drive it there unless I'm almost absolutely certain that it needs repairs or replacing. Normally AppleCare would do home repairs, but they sneakily told me that "if it's a software problem, there may be additional costs" - unable to tell me how high those costs would be. So, utterly worthless.

--

What I'm asking is, are these clear signs that there is in fact a problem with my hardware? It's really important that I know this prior to taking it to the store, because the risks of damaging it during transport aren't exactly small.

I'd really appreciate any advice here.

Thank you.

P.S. "Get a PC" is no valid advice.

[Torhal]

Interestingly, since I installed Lion on my iMac (which is a generation older than yours since I picked it up in January), my fans ramp up very shortly after launching WoW (and I'm merely sitting in Orgrimmar, testing AddOn changes). The machine becomes choppy, as you said, but the main difference here is that twice now my iMac has actually powered itself down.

While I believe (after reading your post) that this is exacerbated by software (something very wrong with Lion and 3D games), I'm still of the opinion that I need to take my machine in to the local Apple Store. Thankfully, I kept my iMac box so it's a matter of re-packaging it and loading it into my car.

[Haleth]

That's interesting (and annoying). If your mac shuts itself down, it's almost certainly overheating. Mine hasn't reached that stage yet, thankfully, though that would be a solid indicator of something being wrong.

Did you ever check the temps on your machine?

[Torhal]

I did, but the only thing that really stuck out is that the temperature of the Skin was 128F...as I write this post, it's 108F. The highest I'd ever seen it before Lion was 120F and that's after having WoW running for a couple of hours. Now, it ramps that high after only a few minutes.

[Haleth]

Try doing the usual, resetting PRAM/SMC/reinstalling Lion if it's dire, then take it in. Let it know how it goes if you can be bothered.

Still hoping someone can shed some light on my situation. /beardrub

[Nibelheim]

Originally Posted by Haleth Try doing the usual, resetting PRAM/SMC/reinstalling Lion if it's dire, then take it in. Let it know how it goes if you can be bothered. Still hoping someone can shed some light on my situation. /beardrub

Seems overheating is a very common issue with the iMac. Tried out smcFanContorl?

[Haleth]

Tried it, didn't really help. It makes it run a couple of degrees lower, but even with the ODD fan at 2000 RPM (which, probably, isn't going to last it very long) the overheating will still occur occasionally.

I'd have asked for a refund, but that's only possible for a week.

[Haleth]

Going to bump this, anyone else with similar problems?