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jeff k · Dec 28, 2009, 03:08 AM

Just came off a G5 for five years. Can't believe the imac is way more powerful and completley contained in such small sliver of space. How do they do it? My G5 was huge and had multiple fans etc.
I am hearing this annoying hum throughout the day I have to say.

turtle777 · Dec 28, 2009, 03:10 AM

Q: New imacs: where are all the fans?
A: Inside

-t

besson3c · Dec 28, 2009, 03:26 AM

Your iMac does have fans, but they don't kick on unless necessary. There are a number of factors that contribute to a machine running cool.

Spheric Harlot · Dec 28, 2009, 04:16 AM

That is completely untrue, AFAIK.

The fans are constantly running, but at extremely low rev (they're huge).
http://eshop.macsales.com/images/Ite...desktopOWC.jpg
http://eshop.macsales.com/images/Ite...desktopOWC.jpg

besson3c · Dec 28, 2009, 01:08 PM

Thanks for the correction, I appreciate the info. It's a good thing I'm being ignored, or else that may have slipped by!

jeff k · Dec 28, 2009, 01:30 PM

What guys think of the efficiency of new imacs (I got 27"), as opposed to the old G5s? ie for cooling and noise and other details.

turtle777 · Dec 28, 2009, 01:36 PM

Originally Posted by jeff k

What guys think of the efficiency of new imacs (I got 27"), as opposed to the old G5s? ie for cooling and noise and other details.

Efficiency for cooling and noise is hard to determine.

Efficiency (the ratio of the output to the input of any system) would be more used for power consumption. (like power used per Gflops)

-t

besson3c · Dec 28, 2009, 01:37 PM

All of the Intel based Macs have a big upper hand on the old G5s. Apple is great at designing their cases, but this comparison puts the Intel based machines at significant crippling advantage.

jeff k · Dec 28, 2009, 05:46 PM

Besson, did not understand that at all. please try again.
I understood Intel is faster than power pc.
Apple designs things well. ok, what were you trying to say?

Spheric Harlot · Dec 28, 2009, 05:53 PM

I think he's trying to say that the intel boxes are vastly more efficient than the G5s were.

jeff k · Dec 28, 2009, 08:25 PM

You mean they are faster? we'll everyone knows that. But this thread is about fans and heat and noise.
not sure what box is either.

Eriamjh · 08:52 PM

The key to quiet, is bigger, but slower fans. Volume, not speed. It's Big Ass Fans whole philosophy.

besson3c · Dec 28, 2009, 08:33 PM

Heat comes from power consumption, and most of your heat originates from your CPU. Intel CPUs consume less power, I believe, and generally run much cooler. It would have been pretty much impossible to build a G5 based Mac laptop because of heat, running cool was never the G5's strong suit.

The G5, IIRC, was built by IBM and the processors IBM was building at the time were for servers, I think the cell processors (used in the Playstation 3) were better suited for small consumer devices, but I think IBM wanted to focus on the console market, forcing Apple to abandon the PPC architecture.

My memory might be a little fuzzy on all of this, but I'm too lazy to Google stuff.

turtle777 · Dec 28, 2009, 08:48 PM

Originally Posted by Spheric Harlot

I think he's trying to say that the intel boxes are vastly more efficient than the G5s were.

Originally Posted by jeff k

You mean they are faster?

No, he did NOT. That's true, but NOT what efficiency is all about.

Do you even understand what efficiency means ?
I gave you the definition above, but you still don't seem to get it.

-t

Eug · Dec 28, 2009, 09:52 PM

My 27" Core i7 is silent most of the time, and quiet at full tilt.

The noise from my G5 2.0 at full tilt was significantly more noticeable, albeit not loud.

jeff k · Dec 28, 2009, 10:58 PM

thanks, my 27" regular, is fairly quiet, but there is a hum... hummmmmmmm. So it's not dead quite, it's there.

So the consensus is that because of the superiority of the intel chip, the new imacs are faster and don't require that huge box.

Then curious why Apple keeps the same exact box for it's Mac Pro's which are not that much faster than the imacs.

besson3c · Dec 28, 2009, 10:58 PM

Originally Posted by turtle777

No, he did NOT. That's true, but NOT what efficiency is all about.

Do you even understand what efficiency means ?
I gave you the definition above, but you still don't seem to get it.

-t

I think you had him at "do you even understand"... You are a charmer!

besson3c · Dec 28, 2009, 11:00 PM

Originally Posted by jeff k

So the consensus is that because of the superiority of the intel chip, the new imacs are faster and don't require that huge box.

No, the G5 iMacs were of a similar form factor.

The Intel chips are much easier to keep cool, because they don't emit nearly as much heat. That's the most concise way of summarizing it, I think.

Spheric Harlot · Dec 29, 2009, 01:41 AM

Originally Posted by jeff k

thanks, my 27" regular, is fairly quiet, but there is a hum... hummmmmmmm. So it's not dead quite, it's there.

So the consensus is that because of the superiority of the intel chip, the new imacs are faster and don't require that huge box.

Then curious why Apple keeps the same exact box for it's Mac Pro's which are not that much faster than the imacs.

Do you think a bunch of expansion slots and four hard drives and 32 GB of memory might have somthing to do with it? I mean, apart from the eight-core machine and the upcoming six-/twelve-core machines, which ARE considerably faster than the iMac?

P · Dec 30, 2009, 06:41 AM

Originally Posted by besson3c

Heat comes from power consumption, and most of your heat originates from your CPU. Intel CPUs consume less power, I believe, and generally run much cooler. It would have been pretty much impossible to build a G5 based Mac laptop because of heat, running cool was never the G5's strong suit.

Yes and no. The first Intel iMacs were cooler than the G5s, yes. The newest iMacs use CPUs that use way more power running flat out than any G5 ever did, but they slow down and run much cooler when idle (which is most of the time). The cooling system in the newest iMacs is also miles better than that in the G5s - trust me, I own both. More space in the 27" for fans, obviously.

Originally Posted by besson3c

The G5, IIRC, was built by IBM and the processors IBM was building at the time were for servers, I think the cell processors (used in the Playstation 3) were better suited for small consumer devices, but I think IBM wanted to focus on the console market, forcing Apple to abandon the PPC architecture.

The G5 was based on the Power4 server CPU, that is correct. To be available at a reasonable price, the L2 cache was cut down from a massive 16MB to 512KB (in the first model - 1 MB in the later ones). L2 cache is there to hide latency to main memory, and the huge cache was put there to hide the high latency of the Power4 memory design. Without that cache, the high latency began to really hurt the integer performance. This meant that while the G5 could beat everything in its class, core for core, when it came to floating point performance, it had serious problems with integer performance. This was helped by the inclusion of the memory controller in the successor Power5, but that never found its way into a desktop PPC CPU.

The Cell CPU would be a terrible fit for a personal computer. The Cell uses multiple in-order cores to do most of its work, and the power of those cores is hard to use well when you don't know what's coming down the stream. Modern CPUs use out-of-order processing. The Cell only has one, fairly weak, out-of-order core, and it would end up doing all the work while the other 8 cores sat mostly idle.

IBM could have made a portable G5. In fact, a G5 clocked at around 1.6 GHz could have been made to fit in a Powerbook if required, but Apple wanted a dedicated laptop chip. To make one such, IBM wanted Apple to pay for the development of a laptop chip and then just pay manufacturing costs per chip. Apple weighed its options on this, and along came Intel with a presentation of their new chip - what would be Conroe - along with a full battery of chipset options that Apple could buy off the shelf rather than develop (the G5 Northbridge was a big part of the reason for the high memory latency). They decided they liked this option better, and went with it. In point of fact they were quite close to switching even before the G5 came along, when we were stuck with 1.42 GHz G4 and a joke of an FSB, but IBM made a better offer then as they developed the G5 and used some of the parts themselves in workstations.