Why does my iMac get so hot?

If mine is working hard like gaming or video converting for a while it gets pretty hot

but not during normal usage

You might want to install iStat Pro from http://islayer.com/apps/istatpro/ to see what the actual temps and fan speeds are. Also, it would help to identify which iMac you have and what operating system level you're running.

Your room temperature is 93º ? The fan speeds look normal, however, the temps look a little high, but not out of spec. When you took the temps, was the system idleing or working?

Hate to say it (Apple sure won't) but I personally know two people whose iMacs had to be fixed/replaced due to thermal failure - motherboards having to be completely replaced. I was so wanting to get an iMac until I learned about these serious overheating issues. This is unlikely to occur if under basic operation like surfing the net, etc... However, heavy gaming, video or audio editing is an ify propostion, so I've been told. Nonetheless, I'm still looking into getting a new Mac, possibly a Mini, to replace my 08 Macbook so I can get into more serious music recording. Can't justify spending $2K on Macbook Pro.

but what about when ur watching videos from youtube, but your not converting or downloading the video

I think BGreg put his finger on the right issue. Your ambient temperatures are very high. Make sure your iMac is located where there's good air circulation and/or away from heat sources.

I downloaded istat pro. The ambient temperature in my house right now is about 78 F. I'm just playing on facebook -- nothing taxing. istat pro says the cpu temperature for my MacBookPro (purchased in December 2011) is 175F! No wonder my computer burns my hands when I move it from one place to another. What can I do about this? Is it normal?

Run the Apple hardware test to see if there are any sensor issues. Max temp for the CPU is around 100ºC or 212ºF.

As to whether it's normal, you might post in the MacBook Pro discussion at https://discussions.apple.com/community/notebooks/macbook_pro

From what I've gathered (I have a 27" iMac)....the iMac's case or "housing" is one big ol' piece of milled aluminum unlike most other desktops and "All In One PC's" (made by Dell, HP etc.) who's cases are mostly made from plastic. The iMac's aluminum case isn't just that way to be pretty, It has a purpose. The housing is the "heat sink" for the machine. Most modern "PC" users will never come in contact with the machines "Heat Sinks" because they are inside the plastic case and use very loud fans to cool those "sinks". Just know that Apple has put it's iMacs thru heating cycles by load that you'll probably never experience. Just make sure that its vents and intakes are clear and clean and you'll be just fine.

this is what my stats are after a few hours of gaming.

somethimes my comp will crash due to overheating. What can be done about this?

Hi BGreg,

Do you think my iMac is running very hot, any danger of it burning out.

Thanks.

Some of the temps , IMO, look a little high for me, but not too bad.

I would be more comfortable is the CPU Heatsink, the optical drive and GPU diode temps were a little lower in temperature than they are currently reading.