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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."
Insufficient cooling?
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.
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.
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...
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
More importantly, it doesn't have to break the 64 bit operations into many successive 32 bit operations. 64 bit operation are not simply 2x32 bit operations, but can be several dozen operations.
An 8-bit microcontroller can perform 64 bit floating point operations correctly. It just takes a long time.
It's hard to make a comparison because for some reason IBM/Apple doesn't want to release official measurements for power usage. Which is strange because they should do really well in that measurement compared to AMD and Intel. Here's their official numbers:
2.4 GHz A64- 89 W
3.4 GHz P4(Northwood)- 89 W
3.4 GHz P4(Prescott)- 103 W
Best guess on the 2.5 GHz G5 is around 65 W.
This page makes a fairly convincing argument that 256 bit CPUs should be enough (basically, there would be no way to exhaust the amount of memory a 256 bit CPU could access, because the number of memory locations is about the same as the number of atoms in the universe).
--Mark
"It is nice to know that the computer understands the problem. But I would like to understand it too." --Eugene Wigner
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
Actually, since most modern CPUs are x86 variants, the floating point registers are usually 80 bits wide (and have been since the 1981 introduction of the 8087).
As far as "complex mathematical calculations" go, 64-bit integers aren't really that big a deal. It's pretty rare to need integers bigger than 2^32 but no bigger than 2^64; floating point usually handles big numbers more flexibly.
The big deal with 64-bit CPUs is 64-bit address pointers and operations on them (which usually aren't more complex than adding and shifting).
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
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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.