what speed does a reduced processor run at?

luminosity

macrumors 65816
Original poster
Jan 10, 2006
1,365
0
Arizona
If i have my 1.33 Ghz processor running at reduced speed in my iBook, what speed is it running at?
 

matticus008

macrumors 68040
Jan 16, 2005
3,336
0
Bay Area, CA
Getting exact figures is very difficult for PowerPC processors, but the speed is generally reduced to somewhere in the 700-800MHz ballpark on most "low power" modes for CPUs, and I'd assume that it would be somewhere in this range.

Edit: 1.33GHz G4 runs at 766MHz according to my developer notes.
 

matticus008

macrumors 68040
Jan 16, 2005
3,336
0
Bay Area, CA
FF_productions said:
Pretty much answered the question...

Yeah, when it's running at REDUCED, your processor will run at half the speed: 1.8 ghz->900 mhz.
Well, the G5s and last-revision G4s can run at half or quarter speed. Earlier processors used a slightly different speed-stepping mechanism that wasn't directly calculable.

I'm just saying this for anyone who uses the search feature and finds this thread later on.
 

yg17

macrumors G5
Aug 1, 2004
14,910
2,515
St. Louis, MO
yellow said:
You could always give:

sysctl -a hw.cpufrequency

A shot and see what you get.
It gave me: 1800000000

So either my computer is really, really, really fast, or it's giving me the number in a really small unit that needs to be coverted to GHz. :D
 

matticus008

macrumors 68040
Jan 16, 2005
3,336
0
Bay Area, CA
yg17 said:
It gave me: 1800000000

So either my computer is really, really, really fast, or it's giving me the number in a really small unit that needs to be coverted to GHz. :D
It gives you the speed in Hz. It's also not terribly accurate, especially on 12" 867MHz PowerBooks, for some reason. On all of my computers, it's always only reported the stock speed.
 

zen.state

macrumors 68020
Mar 13, 2005
2,181
4
matticus008 said:
Getting exact figures is very difficult for PowerPC processors, but the speed is generally reduced to somewhere in the 700-800MHz ballpark on most "low power" modes for CPUs, and I'd assume that it would be somewhere in this range.

Edit: 1.33GHz G4 runs at 766MHz according to my developer notes.
yes. this sosrta thing started around when the 12" powerbook first came out I think. the 867 12" ran at 500 in battery save mode or whatever. 766 sounds right for a 1.33.
 

yellow

Moderator emeritus
Oct 21, 2003
16,033
1
Portland, OR
There have been tons of inacccuracies reported from that sysctl command since day one. It shouldn't be relied upon on PPC architecture. For exacmple, I'm on a "reduced power setting" on my laptop right now, but it still reports the "correct" (normal) CPU speed:

yellow% sysctl -a hw.cpufrequency
hw.cpufrequency: 1249999995

Some older model of Macs running Panther would report sub-rated CPU speeds consistantly, causing people to get uppity. But those were red herring as well. I didn't know the accuracy for this had changed for G5s or for MacTels. Try using:

sysctl -a hw

For a more detailed look at what it will spit out at you.