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iBook 2001 Overclocking Guide 100Mhz bus speed, 600MHz CPU Speed By Tycho Published: 8/21/2000 (Updated 8/22/2001 for Battery Life & Heat Comments)

Disclaimer/Caution: This article is for entertainment purposes only. The author nor the site publisher assumes any liability for modifications you make to your iBook, which voids the warranty and overclocking may affect short or long term reliability. Incorrectly done modifications may cause immediate system damage. OS X TimeBase Issue w/100Mhz Bus Speeds: An iBook owner running a 100Mhz bus speed noted that in OS X 10.0x the clock (time) is about 33% too fast. Michiro Isobe replied this is due to a timebase issue in OS X with bus-overclocked Core99 (UniN) Macs. Just a warning for those that overclock the iBook bus speed. Update - Thanks to Chris for sending an OpenFirmware patch that solved the problem (verified by Tycho - but *use at your own risk*) For those not familiar with OF tweaks, see this 1999 article on sawtooth OF bus tweaking. [Note - I do not know if later OS X versions solved the timebase issue.] Intro | Removing Screws | Resistor Mods | Benchmarks/Game Tests

Step5: Benchmarking/Game Tests So, was it worth it? I took some macbench scores before and after, and also ran some game timedemos (I got the reference results from some forum members as I neglected to run tests prior to modification. Thanks to the members who helped me out). The below macbench scores have the iBook CPU at the top (750cx) and a very tweaked PPC750L with a 1 meg L2 at 1/2 CPU speed at the bottom of each chart. Not too shabby eh? Let's see some Quake and UT scores now (tests run with 384 megs of 2-2-2 RAM, OS 9.2 Open GL, and the July release ATi Drivers) UT 436 cityintro RAVE for Macintosh 640x480 16bit medium texture and skin detail low sound quality iBook 500/66 (Stock): 15.19 min, 54.10 max, 25.57 avg iBook 600/100: 20.39 min, 61.71 max, 31.73 avg Q3A FOUR.DM_66 in Timedemo 1 mode (Quake III 1.29f) 640x480 16bit Lightmap High geometric detail Texture quality 1 notch from max bilinear texture filter low quality sound ALL game options off (no simple items) iBook 500/66 (stock): 1260 frames, 44.77 sec, 28.17 fps iBook 600/100: 1260 frames, 27.8 sec, 45.3 fps WOW!!! Those gains are mind boggling...34% higher min FPS in UT and 17FPS higher average in Q3A (60% increase) This thing is actually a viable gaming machine now. ONI is VERY smooth at 640*480*16. Impressive. If you would like to compare these scores to your current system, email me at dgiessel@mac.com and I can send you the .cfg and .ini files. Here are the Guage Pro and Clockometer screen shots along with some ASP shots (Clockometer seems to be more accurate than Guage Pro with the MHz calculation on the iBook) Pictures: Battery Life Comments: One other thing that many people have been emailing me about is battery life/heat. Battery life at 600/100 is about 15-30 minutes less than 500/66 ...and when the speed is switched down to the 350/100 setting, I get better battery life than I did at 400/66. Additionally, DVD playback is still smooth at 350, so I can actually get MORE DVD playback time than before. Heat/Temperatures: Temps prior to the mod were 40C MAX. After the overclock, they increased to 43C MAX. With the addition of a thin aluminum plate to the top of the chipset and CPU (adding pressure between these chips and the stock heat plate) I was able to get max temps down to 37C, lower than what they were prior to the mod. Another thing to note is that a majority of the chipset/CPU heat is swept towards the back of the portable thanks to the copper wire that apple ran from the cooling plate to the small radiator at the rear of the portable. Thanks to this design, the palm rest is no warmer than it was before even though the portable is dissipating more watts (the reason for heat in the left palm wrest is due to the hard drive being located directly below it). Thanks to the forum members for inspiring me to undertake this project, and to Mike for hosting and running this excellent site that got me started in computers and overclocking. Without you guys this would not have been possible. -David Giessel (aka Tycho) http://homepage.mac.com/dgiessel

Index of iBook Overclocking Guide Intro | Removing Screws | Resistor Mods | Benchmark/Game Tests - or - Back to WWW.XLR8YOURMAC.COM

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