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View Full Version : What's with the adjustable speed of the CPU in the imac G5?


anthonymoody
Sep 28, 2004, 05:09 PM
Sorry if this is a dumb/noob type question, but I understand that the new iMac comes with a standard setting called AUTO which near as I can tell throttles the CPU up and down depending on demand. Further, I understand you can run it in max (or whatever it's called) by electing to do so.

So I guess my question is, since the thing is plugged into the wall at all times and is not drawing down a battery, why'd they do this? Why not run at full speed 100% of the time?

Thanks,
TM

iMeowbot
Sep 28, 2004, 05:14 PM
It allows the computer to qualify for Energy Star (http://www.energystar.gov/index.cfm?c=computers.pr_computers).

Elan0204
Sep 28, 2004, 05:22 PM
It also helps the CPU run cooler if you don't need its full power. This helps reduce fan noise.

By the way, just for future reference, a question like this would be better off if posted in the Hardware Discussion and Help (http://forums.macrumors.com/forumdisplay.php?f=1) forum.

stoid
Sep 28, 2004, 05:28 PM
Just because it's not on battery doesn't mean you can stop worrying about power usage. Someone has to pay the electric bill. ;)

rdowns
Sep 28, 2004, 07:30 PM
Have had my new iMac G5 running on Highest for about an hour now. Fans kicked in once for about 30 seconds and were pretty quiet. I'm leaving it at highest. Who cares if my electric bill is a few bucks more a month?

anthonymoody
Sep 28, 2004, 07:45 PM
Thanks for the replies/explanations. Makes sense, though I agree I'll probably keep mine on full speed :D

BTW I'm a switcher to be - I pulled the trigger on a loaded 20" iMac today after the last frustrating straw with my PC....

And thanks too re: posting in the other forum. I realized that after I posted but didn't know how to change the forum, or if it was even possible, sorry!

TM

Elan0204
Sep 28, 2004, 07:52 PM
Have had my new iMac G5 running on Highest for about an hour now.

Do you notice a speed difference? It seems that if the "Automatic" setting did its job right. you shouldn't notice anything. Automatic should give you the speed when you need it, and let the processor run slower when it can (for example, playing a song in iTunes doesn't need the full processor).

Elan0204
Sep 28, 2004, 07:55 PM
And thanks too re: posting in the other forum. I realized that after I posted but didn't know how to change the forum, or if it was even possible, sorry!

Only moderators can move threads. It's not a big deal to occasionally post in the wrong forum, and sometimes a topic might fit equally well in a few areas, so it can be a judgement call. I just wanted to let you know for future reference.

rdowns
Sep 29, 2004, 03:36 AM
Do you notice a speed difference? It seems that if the "Automatic" setting did its job right. you shouldn't notice anything. Automatic should give you the speed when you need it, and let the processor run slower when it can (for example, playing a song in iTunes doesn't need the full processor).

Haven't done any heavy lifting yet so I can't tell. I plan on spending this weekend installing RAM, getting rid of wires, adding Airport Express to network, moving data and programs over and giving this puppy a good workout. Oh yeah, and watching my Jets go 3-0.

andrewfee
Oct 19, 2004, 10:36 PM
Do you notice a speed difference? It seems that if the "Automatic" setting did its job right. you shouldn't notice anything. Automatic should give you the speed when you need it, and let the processor run slower when it can (for example, playing a song in iTunes doesn't need the full processor).
I've had my iMac for almost 2 weeks now, and I run it on "Highest" all the time now. I have noticed with some programs, games especially (note: I don't use it for games, this was just to test) that the framerate was quite erratic at times, but running on Highest it was smooth. It seems it doesn't always know when it's best to drop the speed or raise it, however I'm sure it's fine for many other uses.

link92
Oct 23, 2004, 07:56 AM
On my Dual 2.5GHz G5, only occasionally do the fans start making more noise, but the performance gain is noticeable...

johnnyjibbs
Oct 23, 2004, 10:16 AM
I did switch my 12" PB to run on Highest when plugged in, but I got fed up with the increased fan useage. Now, I only run it on Highest when working in GarageBand or encoding/burning an iDVD. The only difference with Auto that i've noticed is that the dock magnification isn't quite as silky, but that shouldn't be a problem on an a machine with a 1.6 or 1.8GHz G5 anyway.

Oh, and it's good to save energy where possible :eek: :)

FredAkbar
Oct 23, 2004, 11:14 AM
I have mine on Highest all day, but when put it on Reduced at night so it can fold without being really loud (I'm about 2 feet away from it when I sleep, so it's kind of noticeable).