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Does the 166mhz system bus make THIS big of a difference?

CubeHacker

CubeHacker

macrumors 65816
Original poster
Apr 22, 2003
1,245
257
I recently had the opportunity to pick up a PM G4 gigabit model fitted with a wonderful Powerlogix dual 1.8ghz 7447 upgrade processor. The entire thing with mouse and keyboard was only $50!

I was expecting the speed of the system to blow away my old iMac G4 at home. But to my dismay, the system actually felt slower in daily general usage. Just simple things like loading webkit and loading up a few pages felt about the same, or even less responsive compared to my iMac G4. I tried reinstalling Leopard from scratch and the system responsiveness remained the same. It came fitted with a Radeon 9200. I tried out my 6200 at home which smoothed out system animations, but the system still generally felt slow.

I ran Geekbench and got a decent 1350 score, so I know its performing around the level it should be, but in general usage it just doesn't feel fast. RAM is maxed in the system at 2gb. The only limiting factor would be the system bus. I know people made a big stink back in the day over the aging 100mhz system bus in the old powermacs, but would the jump to 166mhz in my iMac G4 make this big of a difference in system responsiveness?
 
Based on what you've mentioned, I would be inclined to think your bottleneck is probably your hard drive. Maybe you have 5400rpm drives or such?

You didn't mention the drives, so I assume.

I know that my own Quicksilver has gained considerable performance just with SATA drives. I flashed a PC SATA card and it's helped significantly. I will never get anywhere near the full SATA speed of course, but just as an example I recently transfered two different sets of files of apx. 62GB each. Both transfers from one SATA drive to the other completed in roughly 20 minutes or so. A transfer like that on the IDE bus might have taken a hour or more, especially with lower rpm drives.

Just my two cents here.
 
Another thing making the system not feel snappy could be the vid card. The ati 9200 doesnt support full acceleration in leopard. Try putting an ati 9600 at least in there.

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eyoungren said:
Based on what you've mentioned, I would be inclined to think your bottleneck is probably your hard drive. Maybe you have 5400rpm drives or such?

You didn't mention the drives, so I assume.

I know that my own Quicksilver has gained considerable performance just with SATA drives. I flashed a PC SATA card and it's helped significantly. I will never get anywhere near the full SATA speed of course, but just as an example I recently transfered two different sets of files of apx. 62GB each. Both transfers from one SATA drive to the other completed in roughly 20 minutes or so. A transfer like that on the IDE bus might have taken a hour or more, especially with lower rpm drives.

Just my two cents here.
Click to expand...

This makes me think of my xserve g4 dual 1.33. It has the fastest hard drive controllers I have seen on any g4. With blackmagic disk speed test, its holding 60mb/s with a single drive, and it hit 155mb/s with a 3 drive internal raid. These are with 500gig ide 7200rpm hitachi drives.
 
Surrat said:
Another thing making the system not feel snappy could be the vid card. The ati 9200 doesnt support full acceleration in leopard. Try putting an ati 9600 at least in there.

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This makes me think of my xserve g4 dual 1.33. It has the fastest hard drive controllers I have seen on any g4. With blackmagic disk speed test, its holding 60mb/s with a single drive, and it hit 155mb/s with a 3 drive internal raid. These are with 500gig ide 7200rpm hitachi drives.
Click to expand...
Nice! My thought wasn't so much the IDE bus or HD controller itself, but rather the actual hard drive.

For instance, way back in 2010 when I picked up my 17" PB DLSD the drive it came with was the stock IDE drive. I ran with it for a while but it was slow. It was not the controller it was the drive. I installed my WD 320GB HD shortly after that and performance increased significantly. When I put the old drive in my other 17" Mac because it was a larger capacity then the drive currently in there I took a performance hit. It was minor, but it was enough to tell me that hard drives themselves can be a drag on performance.
 
Ah, I don't trust benchmarks!

I had two of these Dual 1,8GHz 7447 (my were Sonnet CPUs).

One was overheating, because the thermal paste dried out. It was getting slower until it freezed. I could reproduce this fast, when I encoded a movie in iMovie. I then watched the CPU load and as soon as it was 70% on both cores, it freezed.

You could try to do this test, too.

I had this in a Sawtooth with 100MHz FSB and it worked both with an ATI 128Pro and a flashed ATI 9200 AGP. I used a 7200rpm WD IDE drive. With the other 7447 Dual 1,8GHz I had no problems in this machine. (sold the overheating one, because I couldn't find the right torx with pin in the middle of the star, to loose the very tight screws of the heatsink. The buyer told me he changed the thermal paste and everything was fine).

I know use a Singlecore 1,2GHz Sonnet 7455 with passive cooler, because the other set up was to loud for me. Keep in mind, that a 7447 1,8GHz is as fast as a 1,42GHz 7455, so the trade-off is not that big (though Handbrake vastly profits from a Dualcore).

Oh, yes, this is a test you can do, too. Use a 5min. movie and convert it with Handbrake on both your iMac and the PowerMac and stop the time. This gives a better picture than using geekbench. (don't use iMovie, because it will take 3-4times longer). Also be prepared, that it takes some hours (23min. took 12:30h on my 1,33GHz ibook G4 with 166MHz FSB! So 2-3h should be expected).
To watch HDD thoughput copy a big file and watch HDD activity in activity monitor or stop the time and devide file size by time.

There is also a Cache enabler/disabler for 10.5 from some manufacturers for some CPUs, I don't remember, if one exists for this CPU.

Is your 9200 a flashed one?

What tasks do you do, when it slows down?
 
eyoungren said:
Based on what you've mentioned, I would be inclined to think your bottleneck is probably your hard drive. Maybe you have 5400rpm drives or such?

You didn't mention the drives, so I assume.
Click to expand...

Both the iMac and the Powermac are running 7200rpm IDE drives. Not the fastest by todays standard, but at least they are on a level playing field. The iMac feels considerably faster in both loading and running software


Another thing making the system not feel snappy could be the vid card. The ati 9200 doesnt support full acceleration in leopard. Try putting an ati 9600 at least in there.
Click to expand...

I don't have a 9600 to test, but I did try my flashed Nvidia 6200 which did help smooth out animations and such. Didn't help as much as I would have liked however.

I had two of these Dual 1,8GHz 7447 (my were Sonnet CPUs).

One was overheating, because the thermal paste dried out. It was getting slower until it freezed. I could reproduce this fast, when I encoded a movie in iMovie. I then watched the CPU load and as soon as it was 70% on both cores, it freezed.
Click to expand...

I had a feeling this might be the issue too. I reapplied the thermal paste to no added benefit. I also tried down-clocking the accelerator to 1.4ghz in the hopes that if the CPU's were throttling, this would help alleviate the problem. The system didn't really feel any faster or slower at this setting, but the heatsink did get notably less hot.

What tasks do you do, when it slows down?
Click to expand...

Its really hard to describe. Most of what I do with the system these days is just basic web browsing. So factors such as page loading, page scrolling, and click responsiveness just stand out. The iMac G4, while still slow by todays standards, just generally feels faster.

Even using apps like mactube to watch video's work better on the iMac - there is a lot more stuttering and hesitation with the dual 1.8 which I didn't expect to occur.
 
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