G4 vs G5

[Joshua]

I was wondering how much faster a G5 1.9 out performs a G4 running at lets say 1.5.

I've never been a huge fan of actuall CPU speed, but have always looked at L2 cache and FSB.

But both the G5 and G4 have the same, so what gives?

I ggogle it and found this, any comments? (http://www.macintouch.com/perfpack/comparison.html)

I'm mainly worried about iPhoto, iMovie and PS CS.

Thanks.

[jer2eydevil88]

Are we talking G4 towers vs. G5 towers? Or is this a comparison between the g4 notebooks and the g5 towers?

G5 cpu's are 64bit and have many other improvements including cache and bus, this is all pretty technical stuff but it makes a big difference. The tasks you specified I perform all on my mac mini without any problem. Granted my roommates g5 dual 2.0ghz tower does it all faster and with greater efficiency.

[Quagmire]

Hmm.... 1.35 GHz FSB( G5) vs a 167 Mhz FSB(G4). Yeah the same alright. :p The G5 is 64 bit and G4 is 32 bit as already pointed out. The G5 can handle more intensive stuff then the G4. And the only things the G4 has going for it is the coolness/power hungryless it is, the 7 stage pipeline(vs 20 in G5), and the better Velocity engine. That is all.

[Joshua]

Are we talking G4 towers vs. G5 towers? Or is this a comparison between the g4 notebooks and the g5 towers?

G5 cpu's are 64bit and have many other improvements including cache and bus, this is all pretty technical stuff but it makes a big difference. The tasks you specified I perform all on my mac mini without any problem. Granted my roommates g5 dual 2.0ghz tower does it all faster and with greater efficiency.

The iMac vs the mini to be specific.

But like I said the FSB and cahe are the same (unless I'm missing something)

I'm strongly considering the mini, have been for awhile, but now that the iMac is out and they dropped the price, I'm mulling that over now...

So, you say you run iMovie and PS on your mini and it runs fine?

What about importing DV? How often do you drop frames?

Thanks for the reply.

[Quagmire]

The iMac vs the mini to be specific.

But like I said the FSB and cahe are the same (unless I'm missing something)

I'm strongly considering the mini, have been for awhile, but now that the iMac is out and they dropped the price, I'm mulling that over now...

So, you say you run iMovie and PS on your mini and it runs fine?

What about importing DV? How often do you drop frames?

Thanks for the reply.

So the iMac. Okay, still 700 Mhz vs 167 Mhz. Still faster. :p Get the iMac. Much better of a machine( especially now with the update) and will last you longer.

[Joshua]

Hmm.... 1.35 GHz FSB( G5) vs a 167 Mhz FSB(G4). Yeah the same alright. :p The G5 is 64 bit and G4 is 32 bit as already pointed out. The G5 can handle more intensive stuff then the G4. And the only things the G4 has going for it is the coolness/power hungryless it is, the 7 stage pipeline(vs 20 in G5), and the better Velocity engine. That is all.

I thought the G4 has a 600MHz FSB? And the G5 1.9 a 633MHz FSB?

[kretara]

The iMac will blow the hell out of the Mini. Period.

Comparing the iMac and the Mini is just not right. The Mini is an entry level machine that has entry level (and some sub-entry level -- 4200 RPM HD's anyone) features.

The Mini is certainly a capable machine and I was able to do some video editing on one with no problems, but the iMac will do it all better....at a steeper price.

[Quagmire]

The iMac will blow the hell out of the Mini. Period.

Comparing the iMac and the Mini is just not right. The Mini is an entry level machine that has entry level (and some sub-entry level -- 4200 RPM HD's anyone) features.

The Mini is certainly a capable machine and I was able to do some video editing on one with no problems, but the iMac will do it all better....at a steeper price.

The Mini's HD are now 5400 RPM with the silent update even though apple.com says 4200 RPM.


I thought the G4 has a 600MHz FSB? And the G5 1.9 a 633MHz FSB?

No. The highest FSB in a G4 is 167 Mhz. The PPC 7448 has a 200 Mhz FSB. Still a meh speed.

[kretara]

The Mini's HD are now 5400 RPM with the silent update even though apple.com says 4200 RPM.

Once Apple updates their web site with 5400 RPM and ALL Mini's ship with that speed, then I will agree with you. Until then, Mini's ship with 4200 RPM drives and you are lucky if you get anything better.

[Joshua]

The Mini is certainly a capable machine and I was able to do some video editing on one with no problems, but the iMac will do it all better....at a steeper price.

Thats the thing, it aint that much steeper anymore.

Since they dropped it to $1299, with all the extra features, I'm re-thinking my potential mini purchase.

[chucker]

I was wondering how much faster a G5 1.9 out performs a G4 running at lets say 1.5.

I've never been a huge fan of actuall CPU speed, but have always looked at L2 cache and FSB.

But both the G5 and G4 have the same, so what gives?

The FSB of a G4 is, at most, 200 MHz. Depending on your old your model is, it may be 167, 133 or 100 MHz.

The FSB of a G5, however, is either at 1:3 (iMac) or 1:2 (PowerMac) ratio. For a 2.1 Ghz iMac, that means the FSB is actually 700 MHz.

Likewise, the G5 also has HyperTransport, which causes a faster and more direct memory connection, meaning much higher bandwidth. The G4 is stuck somewhere in the 2 GBytes per second, I believe, whereas some G5 do upwards of 10 GBytes.

The G4+, which means pretty much any G4 since about 2002, has an advanced AltiVec implementation that he G5 does not feature. In heavily AltiVec-oriented applications, this may bring the G4 at least on par, if not ahead, of the G5.

[Luca]

Guys, frontside bus isn't everything. The G4 has a much slower FSB, but it also doesn't rely as heavily on the FSB to achieve peak performance. Many G4s (at least the ones in PowerMacs and on processor upgrade cards) have loads of L3 cache, which helps make up for the slow FSB. The G5 doesn't have, nor will it ever have, any L3 cache. And like chucker pointed out, the G4's AltiVec implementation is much faster than the one on the G5, which levels the playing field a bit when you use highly AltiVec optimized apps.

It's generally accepted that the G4 and the G5 are roughly equal at the same clock speed (as long as you're using the same speed hard drive and the same amount of RAM in each). Don't buy any kind of "G5 is 64 bit therefore faster" BS, because it's just that... BS. 64 bit just means you can put more than 4 GB of RAM in there. Do you have any apps that are seriously held back by not being able to use 4 GB of RAM? Didn't think so.

[Brad]

Luca is right.

In fact, in some cases the 64-bit implementation is slightly slower than the 32-bit implementation. What do you gain? You get to calculate much larger numbers, but that doesn't affect 99% of your current software. You can access much more memory (more than you can even purchase and fit into any regular PC), but how many GBs of physical RAM are you currently using anyway?

[Joshua]

Well that clears things up alittle, thanks.

I just wish there was some type of benchmark that showed for example how long it took for a 1.9 G5 to encode video vs a G4 1.5. If the G5 took lets say 3 hours, whereas the G4 took 5, then maybe my mini purchase would be worth it, as opposed to the iMac cause I can wait an extra few hours.

But when people say a G5 blows a G4 out of the water, well thats relative. It needs qualification.

[chucker]

What Luca said just about sums it up. On average, in typical applications, in general, exceptions excluded, a G4 with x.y GHz will be just about as fast as a G5 with x.y Ghz.

[Luca]

The real message I want people to take away from this discussion is that you can't only look at one factor when assessing performance. It's ridiculous to conclude that a 3.8 GHz Pentium 4 is twice as fast as a 1.9 GHz G5 just because it has twice the clock speed, right? Well, it's just as ridiculous to say that the G5 is way faster than the G4 just because of the frontside bus. It's also ridiculous to say that the G3 (which used just four pipeline stages) is 5x faster than the G5 (which uses around 20 stages). Clearly it's not. FYI, the original Pentium 4s used 20 pipeline stages, but the latest 3.0-3.8 GHz ones use 30.

Not only do you have to look at a lot of factors beyond just clock speed, FSB, pipeline stages, and cache, but you have to weigh how each factor affects performance in certain applications. Sometimes, you need raw clock speed and a P4 will destroy all else. Other times, the fast AltiVec implementation of the latest G4s will help the most. Sometimes a dual processor system is nearly twice as fast as a single processor system, and sometimes it isn't any faster at all. These problems are all compounded many times over when you try to compare Windows applications to Mac applications.