[BigCanoe]

Hi,

I am looking at a single cpu 500 vs. a dual cpu 500 Power Mac. What would be the quantative difference in performance under OS X? Would it be 10% faster in general use, 50% faster under Photoshop? Assuming all other settings, components, etc are the same.

Thanks,
BC

[AssassyN]

Well if you're talking a 2Ghz + CPU, the differences aren't as extreme. However, going all the way back to a 500Mhz G4 chip, the differences would be highly noticeable. During typical multitasking, your dual CPU's will cause apps. to load faster and run smoother, escp. in SMP-active ones like Photoshop. I'd say you'll easily get your 10% speed increase in general tasks, and a big 'ole increase in Photoshop.

[BigCanoe]

Thanks! The price difference seems to be about 50%, so I wanted to make sure it was worth it, vs. just getting a single, and spending the extra money on some other upgrade.

[Maflynn]

To expound upon what AssassyN wrote, with a dual, OSX will balance the load of programs (specifically threads) on both cpus so tasks complete faster and you have a more responsive system.

I have a cube, it it runs an excel macro in 45 seconds, it takes 100% cpu during that time, other programs that are running in the background slow down noticably. On my dual gig, that same macro executes in 20 second and during that time, only one prcessor is at 100% so my background programs are just as responsive as if I wasn't running that macro.

If you can afford the dual, whether its a 20ghz G5 or a dual g4 500mhz I would recommend it.

Good luck and enjoy.
Mike

[lenox]

With the advent of os x, dual cpu machines really really perform better in just about any multithreaded task there is. Most every medium-to-large app for mac os x is multithreaded anyhow, so you'll really feel it. Other apps make more specific use of dual cpus, too. I don't really know the specifics...but having a dual cpu os x machine makes a lot more sense than the older dual cpu machines that ran classic mac os, and only really shined during lengthy photoshop filters.

My work machine is a 17" imac 800, and my home machine is a dp867 mdd. The difference is increcibly evident in just about everything I do. Granted, this is probably the L3 cache talking, as well...for what it's worth.

[cowerd]

Most every medium-to-large app for mac os x is multithreaded anyhow

No. Most Adobe apps don't know what to do with a second processor. PS shows only minimal gains from a second processor, Illustrator is MP ignorant, and AE as well.

PS would have better gains from maxing out RAM and geting a sick disk array. You might gain 10% from a second processor depending on filters and effects.

http://www.digitalmediadesigner.com/...rks0211082.htm

[joe]

BigCanoe: I own a 500Mhz G4 Cube that I upgraded to a dual 500Mhz G4. From my own personaly experience the single most important factor for increased performance with a dual processor Mac is whether your software supports dual processors or not. The dual processor support is also referred to as being SMP enabled (Symmetric Multi-Processing). PhotoShop is most definitely SMP enabled!! Expect the boost is anywhere from 40-80% from your 2nd CPU (but never double) depending on which filters you're running. There are plenty of PhotoShop and other SMP benchmarks at www.xlr8yourmac.com and www.barefeats.com that you may want to look into. Both sites have archives with benchmarks for older Macs (500Mhz) so you'll have a very good idea of what to expect.

OSX will also seem smoother on a dual 500 vs a single 500 - although this is subjective on my part since there's no way to really benchmark this. Also, it's not as dramatic an effect as you'll see with PhotoShop. OSX does not automatcially speed up apps that don't support SMP. The benefit with OSX is that you'll be able to run more apps simultaneously. But if they're not specfically written for dual processors (SMP), then the boost will be somewhere in the neighborhood of 1-2%. At least that's what I found with my dual 500 G4 Cube. That's why I later upgraded it from the dual 500Mhz to a single 1GHz which was the fastest my Cube ever was.

Which brings up a 3rd option. You might want to look into how much it would cost to get the 500Mhz G4 along with one of the 1GHz+ G4 upgrades. Those have recently dropped in price. And you'll be faster than the dual 500 at all times - not just with SMP apps. good luck whatever way you decide.....joe

[Bill Harrison]

Well, here is a little info from a duallie Owner.

MOST programs are NOT SMP enabled. Lets get that out of the way. By this that simply means they are multithreaded. It is not "special" programming, just a different way of programming, that is not often used on small projects. This should increase in the future as more and more threaded processors are appearing (for example single cpu's with multiple processor units, IE Intels Hyperthreading, and a similair tech being introduced on future G5's).

But, the real increase you will find is in general usability. The great thing is when you have multiple windows open. Each task is a seperate thread, and OS X will put it on a different cpu. Meaning that Multitasking is MUCH MUCH more responsive. And doing multiple things at once, for example listening to music, or encoding movies, etc will not bog your system down. On my single processor, once i started encoding a divx movie, i may as well not have bothered to use my pc as it became horribly slow for anything, even something so simple as browsing the web. Now, with a dual, i can compress a movie, and it shows 100% usage on 1 cpu, but the other is still idling along at 1 or 2 % just waiting to be used for any other tasks i like, including playing games etc with no loss in speed! Try that on any single processor system!


Of course more ram will be a boon on ANY system, single or otherwise. But on a PER app basis, a dual is not THAT much faster. But in a general usage basis, especially for someone like me that always has 5-6 programs running at any time, it makes a WORLD of difference.

[Cadaver]

You'll see the most benefit from dual processors when running two programs simultaneously. Example of where this is easily visible - open iTunes and play something with a visualization. Now, go to the dock (with magnification enabled) and move the mouse back and forth across the dock. The iTunes visualization will not slow down. Try the same experiment on a single processor Mac (no matter how fast). The iTunes visualization will slow way down.

Now, granted, the above is not exactly mission-critical work, but it's effects are easy to see.

This is why I'm seriously considering moving back to the Mac (with a dual G5). A single Athlon is faster for what I do than my old Quicksilver was, but two G5s will, I suspect, murder the Athlon. As soon as I can get my hands on a G5 to play with, I'll probably break down and buy one.

[pinkoos]

I have a dual 867 with 768 MB RAM and I tried the iTunes visualization test noted above and still see considerable slow down/"stuttering" of the visual effects as I slide the mouse over the Dock with magnification enabled.

Any significance to that?

Also, how are you guys monitoring CPU usage? Are you using a special program or one of the OS X utilities? Details would be great....

[joe]

Originally posted by Bill Harrison:
Now, with a dual, i can compress a movie, and it shows 100% usage on 1 cpu, but the other is still idling along at 1 or 2 % just waiting to be used for any other tasks i like, including playing games etc with no loss in speed!

Your multitasking a video game while compressing a movie without any loss in speed??? If so there's no way in hell you're running the dual 500 setup that BigCanoe was asking about!!! I actually owned a single 500 - upgraded to a dual 500 - upgraded to a single 1GHz. All other components being precisely equal. And those components weren't lame either: OEM GF3, 1.5GB 2-2-2 PC100 RAM, 7200rpm HD, etc. And of those 3 cpu setups, only the last could even come close to your level of performance.

There are plenty of reasons for this. The improved altivec, memory bandwidth / management, and larger/faster L3 caches in later model G4s, a minimum amount of processor power that OSX needs to run smoothly, not to mention that most video games (except solitaire) choke at 500Mhz even if you throw a GF4Ti into the mix!!! I've no idea what dualie your running, but I suspect a dual 1GHz or close. Because in that case you would have a respectable 1Ghz G4 available for both applications simultaneously (compression + video game). Of course OSX really doesn't work that way, but it's a good enough analogy for comparison to a dual 500. And that's what the original post was all about.....joe

[LeeG]

Along these same lines, would upgrading my G4/500 AGP to a dual 1GHz card or a Single 1.42 card be a better move?

Seems like in raw speed, I'll see better performance from the 1.42, but the dual may improve responsiveness...any thoughts?

Lee

[Hiramw]

Hi,

I recently upgraded my Dual G4 450MHz to a single 1.4GHz G4. I ran some benchmarks before and after the upgrade. The first set of numbers are from the Dual 450 and the second set are from the single 1.4GHz. All other the things, RAM, hard drive, graphics card and OS are the same.

(1)=Dual G4 450MHz (MPC7400) (2)=G4 1.4GHz (MPC7455)

XBench Overall Score (1)=62.44 (2)=105.19
XBench CPU (1)=47.13 (2)=153.92
XBench Quartz (1)=69.62 (2)=127.28
XBench OpenGL (1)=54.06 (2)=127.08
Altivec Fractal Carbon (1)=2981.8 MegaFlops (4.5 sec) (2)=4885.9 MegaFlops (2.7 sec)
Skidmarks GT (1) Int:41 FP:53 Vec:45 (2)=Int:140 FP:140 Vec:140
UT 2003 Asbestos-Bot (average fps) (1)=14.34 fps (2)=20.36 fps
UT 2003 Asbestos-Flyby (average fps) (1)=43.75 fps (2)=75.69 fps
UT OSX version (average fps) (1)=33 fps (2)=51.7 fps
Quake 2 OS X version (average fps) (1)=77.8 fps (2)=131.9 fps
Export iMovie Tutorial as QT movie (1)=112 seconds (2)=48 seconds

I bought the upgrade from fastmac.com and so far it has been completely reliable.

If you are comparing a single 500MHz G4 to a dual 500MHz G4s, then I would take the dual CPU without hesitation. However, when you are comparing a single 1GHz G4 to dual 500MHz G4 it's not as clear cut. At some point a single G4 is faster than slower dual G4s at every task.

Hiram

[Simon]

Originally posted by LeeG:
Along these same lines, would upgrading my G4/500 AGP to a dual 1GHz card or a Single 1.42 card be a better move?

Seems like in raw speed, I'll see better performance from the 1.42, but the dual may improve responsiveness...any thoughts?

I think you already summed it up in a fine way. The 1.42GHz will be faster, clearly. As long as you only look at one task. If you are doing two tasks, the dual 1GHz will likely get them done faster together.

Therefore, which one to buy (aside from the price) depends on how you work. If you tend to do mainly one thing at a time (like browse the web with only Mail.app running in the background) the single CPU will be fine and may be the better choice (especially if it is cheaper). But if you normally do multiple tasks side by side like compressing AV in the background while working on a PS document the dual will be a better choice.

It really depends on how you work. IMHO there is not just one single correct answer.

[TimmyDee51]

I know this doesn't matter for you, but I found it interesting anyway.

Onstage demos at the Macworld Creative Pro Conference & Expo highlighted two of the G5's strong suits: floating-point math and lightning-fast graphics. Apple confessed that in a single-processor configuration, the G5 CPU is slower than a solo Xeon. The Power Mac G5's turbocharger kicks in when you install the second CPU.

http://www.infoworld.com/article/03/...html?s=feature