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What Makes Apple's Power Mac G5 Processor So Hot
An anonymous reader writes "58 million transistors can drive a lot of power. Apparently, Apple appreciated the choices IBM processor architects made when designing the 970 family. This article provides the 64-bit architecture big picture for the 970 family (A.K.A. the Power Mac G5) and the critical issues in IBM's 64-bit POWER designs, covering 32-bit compatibility, power management, and processor bus design."
If it's so hot, maybe it's not cool enough.
Insufficient cooling?
Basically, we took one of our superchips that go into superservers, with a gitastic cache and frontside bus, stripped it down a bit so we don't cut into our own market, and gave it a new name. Isn't that cool?
The difference between spam and poop is that you don't have to dig through septic tanks looking for real food. -- Me
"Backups are for wimps. Real men upload their data to an FTP site and have everyone else mirror it." -- Linus Torvalds
I was able to hold my hand on the heatsink and it was barely warm.
It could be because there's inadequate conduction between the CPU core and the heatsink. Check the temperature monitors to make sure it's actually as cool as you hope it to be. It could be that just most of the heat is staying in on the CPU, which would be a bad thing. Hopefully you've already checked this though.
-GillBates0, 2004.
An Indian-American Hindu committed to non-violent thought/speech/action alarmed by the global explosion of radical Islam
The fan belt on its search engine doesn't drive the radiation air emission unit fast enough! SHE NEEDS MORE POWER!
They should make the G5 powerbooks have a teflon underside.
"Turn it over, and you can cook dinner".
One side-effect of 64-bit computing that I don't hear a lot of discussion about is the increase in the size of a pointer. A standard implementation of a linked list of integers will now be 50 to 100% larger (depending on if you use 32 or 64 bit integers), simply because the pointers take up more space. If I bought a 64 bit system, simply because it's the "Best", but only got 1GB of RAM, I have less useful memory, because the pointers take up all of my physical RAM. Do the architects of these systems take this into account?
Sometimes I doubt your committment to SparkleMotion!
I'll probably get modded down for saying this, but I have Karma to burn...
That article is some crybaby whining about how expensive the G5s are. "Apple is so dumb. Why would anyone pay that much for a CRAP computer," is what the article sounds like. I think that guy needs to take his superior knowledge elsewhere and try some benchmarks ("512K of cache isn't competitive for $3000")... apparently it is because it's winning benchmarks and people are buying them. Just because you can't afford it doesn't mean it's a bad computer (doesn't mean it's a good computer either). This guy needs to grow up and write an article with facts instead of emotions...
My other car is first.
Most importantly, it can address up 2^64 bytes of memory. And yes, that generally implies 64-bit integer GPRS. BTW, vector operations on x86 (MMX) also operate with 64 bit registers, but it can only access 4G (32G if you use the extended bits "hack").
The Raven
Holy fuck dude... your room temp is 109.4 degrees Fahrenheit (thank you google)?
Open a window or buy an air conditioner or something!
I've just signed legislation that'll outlaw Russia forever. We'll begin bombing in five minutes.
Does anyone have the numbers to compare how many watts of power the G5 uses vs a similar AthlonXP or AMD64? Ie, I'd like to see how a 2.0 or 2.5 GHz G5 compares to a 2.0 or 2.5 GHz AMD processor.
Capable of addressing an astronomical 18 billion GB, or 18 exabytes, of memory,
I know the first 2 digits are 1 and 8, but 2^64 bytes is still 'only' 16 exabytes...
Obligatory PC Weenies link that fits the topic at hand.
The PC Weenies: 11 Years of Online Tech 'Too
umm, what heat problem? the 9 fans and liquid cooling are in their respective models to solve a SOUND problem. not a heat problem. but then if you bothered looking up statistics on the G5 you would not be able to bash the mac would you?
I am the Alpha and the Omega-3
The notable exception is the Arm's thumb instruction set (it's cool).
The sad part "my address bus is bigger than you" is going the "I have more MHz than you" way soon as parallel CPUs (mulit-core or otherwise) become cheaper.. 90% of our tasks are better done parallel than using a single fast chip . Hell , half of the tasks really don't need anything beyond a 300/400 mhz clocks.Quidquid latine dictum sit, altum videtur
The power coming out of a chip is marginal; it's pretty much all converted to heat.
Cheers!
-- CD
Use ISO 8601 dates [YYYY-MM-DD]
Your iMac G5 has two fans. Not much space left for additional cooling, really, without interfering with the current cooling setup.
Your PowerMac G5 has nine fans. Again, not much space left for additional cooling without interfering.
And get this, the PowerMac G5 already uses a liquid cooling setup. The only possible additional mod is to hook the current setup to a resevoir and radiator on the outside of the case, as the inside already has a radiator per CPU and something like a 120mm fan per CPU.
GPL Deconstructed
The *BIG* thing for x86 for "64bit computing" is not in fact the 64 bitness but doubling the number of GPR!
As the PPC instruction set is sane (x86 is not, urgh), beside the extra-instruction needed for 64 bit computing, there are very few difference between a PPC running on 64bit code or a PPC running on 32bit unless of course you have an app which needs more than 4GB of memory or do lots of 64-bit integer calculation..
You live in the Kalahari desert?
... 14 hours a day :-)
He might live in Tucson or Phoenix, Arizona; the Sonora-Arizona desert is quite a hot place in summer. Around Hermosillo, Sonora, there's a permanent high-pressure system which pushes off any clouds coming our way, so there's uninterrupted sunlight some
All through July and August, the normal, everyday noon-time temperature is over 45 C, 47 C is not really all that surprising. Once I was out in the street at 50 C.
Being a desert, it cools down quickly at nighttime; but when there's no breeze to take away the heat, it sucks evilly to be at 10 PM and still at thirty-something C. So, being at 43 at night is awful. I know how you feel though.
The best part is the faces others make when they find out about summer in Hermosillo: "But, that's impossible!" Naa, just a bit warm.
-gus
Introduction to 64-bit computing
/wishes he had exa-bytes of memory right now... VS.NET on WinXP is a PIG!
There's an informative link at the bottom of the article for those requiring a bit more insight into the effect of 64-bit computing.
-- All views expressed in this post are mine and do not
-- reflect those of my employer or their clients
is there another reason to use liquid cooling, other than excessive temperature?
Not sure if this is the reason, but its not just a matter of amount of heat generated. Its the amount of heat generated in a given area. So if you generate the same, or even less, heat in a smaller area, you may need to resort to something more efficient that air cooling to do the job.
Just because you can't afford it doesn't mean it's a bad computer (doesn't mean it's a good computer either).
Hear hear.
I've priced out equivalent machines to the current Apple offerings, and you do indeed get what you pay for. A dual-CPU 1.8Ghz Powermac is around $2500 sans monitor. Price out a dual-Xeon or dual-Opteron and you end up at around $2000-$2500 for a comparable system.
Where Apple might be missing the boat is in the ultra low end where you can buy a system for $600. (But why should they try to compete down there where margins are razor-thin?)
Wolde you bothe eate your cake, and have your cake?
The quest for CPU power has been largely defeated by bloated software in applications and operating systems. Some programs I wrote in Basic on an Apple II ran faster than when written in a modern language on a G4 Dual-processor Mac with hardware 1,000 times faster.
Come on. What language are we talking about here? My basement collection includes a II+, a IIe, two IIcs and a Franklin compatible. I challenge anyone to come up with a program in Applesoft that runs faster on one of my museum pieces than on a modern Mac using C++, Java or even Perl. I mod his article -1 for troll.
While software has become bloated and to some extent inefficient, people often forget that we expect a lot more from our computers now than the single-tasking 80 column display days.
My cat can eat a whole watermelon
Simple. Since we've got a computer capable of simulating the entire universe, we'll just use it to simulate a universe which contains a computer which is capable of simulating more than one universe.
Where Apple might be missing the boat is in the ultra low end where you can buy a system for $600. (But why should they try to compete down there where margins are razor-thin?)
Because poor college students like me, who buy $600 computers is going to buy a PC. And when I get out of college and have the means to drop $2500 on a computer, guess what I'll probably buy.
Actually, the two real reasons why Apple doesn't sell low end machines is that it would undercut sales of their more expensive machines, and totally destroy the second hand Mac market (where used Macs are way overvalued, IMHO). Without a strong second hand market to sell a used Mac for a good price, people will be less likely to buy their high end machines.
I have mod points, but I figured I'd answer your question instead.
When you do a die shrink, you can lower the power required at particular clock rate, or you can run at a higher clock speed with the same power dissipated. So when IBM went from 130nm for the 970 to 90nm for the 970FX, the top clock speed went up from 2GHz to 2.5GHz. Other than the process change, I believe there were very few changes to the chip.
Now, when you go from 130 nm to 90nm, the linear dimension across the chip is ~70% of what is was, and the area of the chip is (70%)^2 or about 50% of the previous chip.
Lets use some numbers, these may not be 100% accurate, but they'll explain the basic concept. The 2GHz 970 had a die size of about 121mm^2 and put out a maximum of 42W. That is about 350mW/mm^2. If we assume that the 2.5GHz 970FX has that same power consumption, but has a die size of 60mm^2, then the 970FX will produce 700mW/mm^2. So you have the same amount of power, but you are trying to suck it out of a smaller piece of silicon. So you need much more efficient cooling to keep the chip temperature the same. Hence, the liquid cooling system in the dual 2.5GHz G5.
--
The internet is the greatest source of biased information in the history of mankind.
for literal heat, this puppy is pretty hot.
my dual 2.5GHz PowerMac G5 idles at 52C (125F) on CPU A and 50C (122F) on CPU B. the memory controller is actually one of the hotter things, it idles at 62C (143F). however, it's not the hottest thing, of course: at full load (DVD rip+encode or playing 15 videos at once + MP3 + tasks + flicking around Exposé) both CPUs have hit a max of 83C (181F) (the computer is supposed to automatically sleep around 90C or so).
so why so effing hot? i mean, this idles at the max temp my athlon 2500 peaks at! it certainly idles at a hotter temp than it needs to, but i have no problem with that: the system runs the fans dynamically to keep the noise down, so at idle it's not as cool as it could be. the difference in noise in my room when i sleep the athlon is ridiculous - the G5 sounds like a slightly loud external hard drive that's spun up. the system also has a liquid cooling system to quench the processors. this seems to just keep the processors within their range. the value that i see in it is response to new heat - the CPU temps flick around a lot and are very responsive to load and the loss of load. after ramping up the CPUs to >80C, it take about three or four seconds after the load drops for the CPU temps to drop 15-20C, then maybe a total of ten or twelve seconds to drop to idle temp.
for some real-world perspective... a DVD rip+encode with HandBrake with using ffmpeg engine, MP3 audio, 2-pass encoding, and gunning for your average 700MB movie time (800-1300kbps?) takes slightly less than the length of the DVD. an hour and a half long movie took about and hour and fifteen minutes to get on to my hard drive. MP3 ripping in iTunes will run up to 28x, but it's not fully loading the processors so i wonder about a drive read bottleneck. the first night i got it, i was at a loss for how to really test the speed on it, so i just decided to open up a shitload of videos. basically i played a DVD (fluff, the GPU does that), opened up something in VLC, opened up about 13 videos in QuickTime of various sizes and formats, played some MP3 music (fluff again, that's ball sweat of a cutting edge proc), and still had enough processing power to comfortably navigate files, chat, browse web pages, and flick around Exposé. around all of these things plus one is when a few of the videos would start stuttering and expose would start dropping frames to keep collapse speed uniform. anything past this would really start robbing time from videos.
all in all? it's fast. it's quiet. it gets hot, but it takes care of itself. coming from a 375MHz G3-upgraded PowerMac 7600 (vintage '98), i'm not doing too shabby. i just decided i'd scramjet at mach 7 to the top of the pack and then sit there for another few years.
- emilio
neurostyle dot net - it's all in your head
But that's why people buy macs. To use photoshop quickly. So how long a filter application takes is very relevant.
:)
I don't have a mac here, but opterons and g5s are probably similar. Pick the one you like, they're both expensive
My other car is first.