Question About G4 Processor???

When MR members here say that the G4 suck we do not mean clock speed we are talking about the overall package. Most important the bus speed.

G5 chips has a much faster and larger FSB when compared to the G4 chip, if the G4 chips has as good of a bus as the G5 chips, people here would not be complaining.

intel chips have a faster FSB when compared to the G4, though they chips are crippled in other ways.


Does this sort out your question.

 

hmm they dont understand PPC instructions?

i aggre that their is too much G4 bashing going on! its not all about clock speed etc. my G4 400 is faster than my P3 733 for web browsing, email and everyday tasks like that, when i comes to movie rendering, large photoshop files and quark it does lag a little but we are talking about 1991 here! the prod is that a lot of people are using their portables for MAJOR tasks which maybe their where not quite build for.

 

jumpman25:

Depends entirely on what your test is. In general, however, the P4 is faster.

Bad assumptions there. Consider: the 1.7ghz P4 was a generation 1 core, with 256k L2, and a 400mhz FSB. The 800mhz G4 was a generation 1 "long pipe" G4, with 256k L2, 2MB L3, and a 133mhz FSB. Time passes. The 3ghz P4 is a generation 2 or 3 core, has a 800mhz FSB, and 512k or 1MB of L2. The 1.5ghz G4 is still the original core (simply made smaller), with 166mhz FSB, and 512k of L2. (No L3.) ...pause... So the P4 nearly doubled clock, it doubled FSB, doubled or quadrupled L2, and went through 1 or 2 new cores. The G4 also nearly doubled its clock, increased FSB by only 25%, doubled its L2, lost its L3, and didn't change design.

Intel and AMD change and evolve their products. Moto... sometimes releases a die shrink. Probably sometime soon they'll have G4's with on-die memory controllers and whatnot, which is great, but the core will probably be exactly the same as it has been since Apple's first 733mhz G4 (Moto 7450), which was introduced in January 2001.

Seriously, the best G4 you can buy today is somewhat less than twice as powerful as one you could have gotten 4 years ago.

The P-M has a 100mhz QDR bus, do a 400mhz data rate. It'll be moved up to 533mhz soon enough (133mhz QDR).

The big weakness of the G4 vs the P-M are:
1) FSB throughput: years behind.
2) L2 cache: new P-M's have 2MB on die.
3) Double-precision floating point: AltiVec can't help here.

 

Very succinctly put. Actually that was one of the least convoluted comparisons I've ever seen

 

I have a few questions:

1) If Pentium M's have double precision, what exactly do the G4's have? Single precision?

2) And does the amount of precision have any sort of bearing on the whole FLOP argument?

 

Mav451:

They both support both single and double. The thing is, AltiVec only supports single precision floating point math, so the G4 looses its strongest asset and has to rely on its scalar floating point unit. (Remember the G5 has two scalar FP units, not one.)

Not really. Single precision is typically gona be a higher flop score.

jumpman25:

I'd say the P-M is a better chip, but if Apple ever ships that upcoming G4 with on-die memory controllers, that will go a long ways towards closing the gap.

There is a long-pipe and a short-pipe G4, the short pipe one being the one closley related to the G3, and like the G3, it is no longer offered in an Apple product. Both designs are pretty short compared to G5's, Athlons, or most anything else.

FSB bandwidth is less important than a lot of people think. Its a lot like the "megahertz myth" with CPU clocks. Some generalizations follow: 200mhz DDR (100mhz x2) wasn't any faster than PC133. 533mhz DDR2 (133mhz x4) really isn't any faster than DDR400. A P4 at 1.4ghz wasn't any faster than a P3 at 1.0ghz. You get the pattern: when technology is redesigned for higher clockspeeds, often more steps are added so that latency (access to memory, or an instruction through the processor) isn't lowered much. Why? Because its bounded by the speed electrons can move.

So, the 166mhz FSB on a G4 is kinda lame, but at the same time it can still get small things from memory more-or-less as fast as a G5's 1.25ghz FSB, because in both cases the limiting factor is more-or-less how fast the electrons can move.

This is not to say that fast FSB's are a waste. A fast FSB could be compared to a train, capabile of hauling huge amounts of stuff at once, but only in the case where all the stuff is well-ordered. A fast FSB is great for streaming video, as an example. However, if your dealing with random data, or not very much data, the old G4 FSB is fine.

Yeah, Moto spun off Freescale. Old timers like me still say "Moto".