Mac Daniel's Advice

Speeding Up a Beige G3

Dan Knight - 2002.10.28 - Tip Jar

Although you can run Mac OS X on a stock beige G3, but you may find things a bit sluggish. Although comfortable under the classic Mac OS, under OS X performance is sluggish. Blame it on an underpowered CPU (well, at least as far as OS X is concerned) combined with outdated video, a slower hard drive, and a slow data bus for the drive.

We've had a beige G3/266 with 288 MB RAM and the stock 4 GB Quantum Fireball hard drive since early 2002. It's one of three Macs we currently have loaded with Mac OS X (the other two are my wife's 14" iBook and my 400 MHz TiBook). The beige G3 is connected to a 17" monitor, runs Mac OS X 10.1.5, and lives in my youngest son's bedroom. It's one of our testbeds for OS X browsers.

Until 12 days ago, the only hardware upgrade we had performed was bumping RAM from a paltry 64 MB to 288 MB (we had to remove one 32 MB DIMM in the process). From everything I'd read, too little memory is the leading cause of poor OS X performance. That's something I plan to test later - after I've removed a few other bottlenecks.

Beige G3 Bottlenecks

The Quantum drive may have been a decent performer in its day (1997) with 10.4 MB/sec. maximum throughput, but the beige G3's IDE bus is rated at 16.7 MB/sec., so a faster drive should make a noticeable difference.

We already tested a Seagate Barracuda drive in the G3 earlier this year and found that it could reach 15 MB/sec. peak throughput - probably limited by the IDE bus on the motherboard. Another bottleneck to address is the slow IDE bus. Fortunately, ATA-66 and faster cards are readily available and reasonably priced today.

The other significant bottleneck is the ATI 3D Rage II video on the motherboard. Regardless of how much video RAM is installed, this is a very slow graphics system by today's standard. In the future we'll be trying to pick the best value in a PCI video card that's supported by OS X.

For our purposes, gaming performance is not an issue. We've got a lead on an ATI Rage 128 GL with 16 MB VRAM, which was the standard video card on the 1999 blue & white G3. From the research I've done, this looks like a very good choice. More when we have one to test.

We've also got a faster 333 MHz CPU to see how much difference that makes. From my research, it seems quite likely we'll be able to overclock it and turn our reliable old G3/266 into a speedster G3/400. More on that after I obtain some thermal paste and play with the jumpers.

For now, we have replaced the G3/266 CPU with its 512 KB level 2 cache with a G3/333 and a 1 MB level 2 cache. Performance is much nicer all around.

A Faster Drive

We've got a couple larger, faster ATA-66 hard drives around here - the previously mentioned Seagate Barracuda and an IBM Deskstar that I used to use in a FireWire enclosure. We've also got a wicked fast 80 GB Western Digital 7200 rpm drive with an 8 MB buffer that we'll soon be using for backup. This is an ATA-100 drive.

I already detailed the nightmare we found ourselves in a week ago (see Mac OS X and a Beige G3) that ended up with us zapping the PRAM, pressing the cuda switch, using a CD-ROM lens cleaner, and doing a completely fresh install of OS X on the IBM drive. I'm very glad that's behind me.

The 30 GB drive is partitioned into a 7.8 first partition, as required by OS X on the beige G3 and some other early Macs, with the balance used for Mac OS 9.2.2, all of our classic applications, and our personal files.

How Much Faster?

It took way too many days to get there, but we finally got OS X installed and running on the IBM Deskstar. Then we moved OS 9, the old apps, and some other files to the second partition. This both clears up a lot of space on the OS X partition and lets us run diagnostics from the OS 9 partition if and when necessary. This should also make it faster when running Carbon Copy Cloner to clone the OS X partition on the next hard drive we test.

One thing I've learned is that CCC has problems with "old world" Macs such as the beige G3. The recommended workaround, which I tried, is to first install Mac OS X on the destination drive and then use CCC to clone everything to the new drive. Unfortunately, when we tried it, the formerly bootable drive refused to complete the startup process again.

If you're using a beige G3, don't expect Carbon Copy Cloner to work for you. It's been great on other Macs, but this problem seems insurmountable.

Anyhow, we finally got X up and running on an 8 GB partition on the IBM Deskstar, ran all the updaters to bring it to 10.1.5, and ran some benchmarks. Here are the results:

Let 1000 Windows Bloom

CPU     resolution   bits     time  
G3/266   1024 x 768   16-bit   127 sec
G3/266    832 x 624   24-bit   185 sec
G3/333   1024 x 768   16-bit   101 sec
G3/333    832 x 624   24-bit   149 sec

Switching to a faster CPU trimmed 20% from this benchmark. The 333 MHz G3 fully accounts for the difference, so the onboard video appears to have no impact on this benchmark. Interesting that video is so wed to the CPU under OS X, not the video hardware.

SpeedRun 1.1.3

CPU     drive    resolution  graph  drive   CPU    RAM
G3/266  Quantum    832x644    110    n/a     86    173
G3/266  Quantum   1024 x 768    115    n/a     89    177
G3/333  Deskstar  1024 x 768    158    177    115    222

We were unable to run the drive tests on the stock Quantum drive due to a lack of free space on the drive. We will go back and test it later. All tests are run at 16-bits (thousands of colors), since that is the only way SpeedRun works.

In this case, the graphics results with the faster CPU and larger cache are more than 25% faster. At 37% faster, the improvement may be partially due to the larger cache, something we'll be able to test more thoroughly later when we play with overclocking.

The processor benchmark shows the G3/333 is 29% faster, a bit more than the 25% predicted by processor speed alone, demonstrating that the larger, faster level 2 cache is helpful.

The RAM benchmark shows an across the board 25% improvement.

Round 2: The Barracuda

Rather than go through the whole process on the internal bus, I decided to connect the Seagate Barracuda drive to an Acard Ahard. This PCI card supports up to four IDE/ATA-66 drives (two masters, two slaves) and "tricks" the Mac into seeing them as SCSI drives.

An interesting and unexpected side effect is that the OS X installer was perfectly willing to install itself on the second partition, which was larger than 8 GB. That means that I probably didn't need to partition the drive, but since I'd already done so, I wasn't going to experiment right away. Maybe later.

Testing Under Mac OS 9

We ran some preliminary benchmarks under Mac OS 9 - mostly because we've used these tests for years and have other results for comparison. Keep in mind that we did not play around with the disk cache setting, leaving it at the 8 MB default setting, which really boosts benchmark ratings.

Speedometer 4
CPU     cache   drive      CPU    disk    math
G3/233  512KB  Quantum    21.04   3.55   745.3
G3/233   8 MB  Quantum    21.03   4.51   745.4
G3/333   8 MB  Deskstar   26.29   4.23   931.3
G3/333   8 MB  Barracuda  26.52   4.19   931.7

The 333 MHz CPU comes in at 25-26% faster, and the math score is 25% faster, none of which is unexpected. What is surprising is that the Seagate Barracuda on the Acard, the IBM Deskstar on the internal bus, and the poky old Quantum Fireball scored within 10% of each other. I'm guessing this is due more to the size of the disk cache than to disk performance.

MacBench 5
CPU     cache   drive      CPU    math    disk
G3/233   8 MB  Quantum     830     890     984
G3/333   8 MB  Deskstar   1115    1114     805
G3/333   8 MB  Barracuda   n/a     n/a    1095

The IBM Deskstar drive tests slower than the Quantum using the internal IDE bus, which is unexpected. The Barracuda connected to the Acard outperforms the old Quantum by only 11% in this benchmark.

SpeedRun 1.1.3
drive tests            graphic drive  CPU    RAM
Deskstar, internal bus    n/a   151   216   1481
Barracuda, Acard          378   167   220   1486

I didn't use SpeedRun under OS 9 before swapping in the faster processor. SpeedRun only places the Barracuda on the Acard at 10% faster than the IBM Deskstar on the internal bus.

ATTO ExpressPro

We went back to our original tests of the Quantum and Seagate drives in January, which were run at the stock 266 MHz CPU speed. These tests were performed with an 8 MB disk cache.

Quantum 8 meg test

Testing the Quantum gives us peak read and write speeds of just under 10.5 MB per second and sustained speeds a bit under 10.4 MB/s.

Barracuda 8 meg test

On the same internal bus, the Barracuda has peak read and write speeds in excess of 15 MB per second, a sustained read speed of 14.2 MB/s, and a sustained write speed of 15.6 MB/s. We speculated in January that the Barracuda was probably bottlenecked by the IDE controller on the G3 motherboard.

IBM Deskstar

The IBM Deskstar on the same internal bus - but with a 333 MHz CPU - has a peak read speed of 16.15 MB/s and a peak write speed of 15.1 MB/s. Again, performance is probably constrained by the bus on the motherboard.

Seagate Barracuda

We next tested the Seagate Barracuda connected to the Acard Ahard drive controller, which let it go well past the 16.7 MB/s limitation of the onboard IDE bus. Overall, we're looking at about 3 times the hard drive throughput whether reading or writing data. Although some of the benchmarks don't show much of a difference due to our testing with a large disk cache (you wouldn't believe how slow this machine is if we crank the disk cache down to 512 KB for benchmarking - it's excruciatingly slow), this drive is an impressive performer.

Testing Under Mac OS X

Let 1000 Windows Bloom
CPU       resolution    bits     time  
Deskstar  1024 x 768   16-bit   101 sec
Deskstar   832 x 624   24-bit   149 sec
Seagate   1024 x 768   16-bit    95 sec
Seagate    832 x 624   24-bit   141 sec

In a completely unexpected development, Let 1000 Windows Bloom, which is designed to measure how quickly OS X can open and close 1000 windows, runs faster with the Seagate Barracuda on the Acard Ahard than it does with the IBM Deskstar on the internal IDE bus. This merits further investigation, but it may be due in part to a clean install of OS X 10.1.5.

SpeedRun 1.1.3
CPU      drive    resolution   graph  drive   CPU    RAM
G3/333  Deskstar  1024 x 768    165    179    115    222
G3/333  Seagate   1024 x 768    165    182    115    222

There's a big surprise - under OS X, the Barracuda benchmarks less than 2% faster than the IBM Deskstar.

Startup Time

I clocked startup time for the G3/266 with the Quantum drive at 128 sec from pressing the power button on the keyboard until the dock appeared on the desktop. Switching to the faster CPU and hard drive has improved that. With the 333 MHz G3, the beige G3 launches OS X in about 90 seconds with the Deskstar drive and about 87 seconds with the Barracuda.

Still to Come

We still need to pick up a second ATA-66 data cable so we can test the IBM Deskstar drive with the Acard, and after that we'll be trying the 80 GB Western Digital 7200 RPM drive with an onboard 8 MB data buffer. That one may push the Acard to its limit.

We will be picking up some thermal paste and experimenting with overclocking. Current goals are to test the 266 MHz processor at 300 and 333 MHz, scale back the 333 MHz G3 to 266 MHz just to see how much difference the cache makes, and then attempt to push the faster CPU to 366 and 400 MHz. We anticipate no problem at 366 MHz and suspect 400 MHz may be very doable.

After that, we should have a Rage 128 PCI video card to test. With better video circuitry and 16 MB of VRAM (the beige G3 has only 2 MB), we hope to see some real differences there. LEM

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