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Why did Apple leave off the L3 cache on some G4 machines?

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I have 2 Quicksilvers that I use. One has a 1.25Ghz G4 upgrade with 2MB L3 cache and is pretty fast. The other machine is a G4-800 with no L3 cache and kind of slow. Recently I decided to upgrade the 800 unit and found a G4-867 with 2Mb L3 on ebay for $10 shipped. Xbench 1.3 shows the different between the 800 and 867/2MB is pretty huge (if that benchmark is to be believed). The 1.25Ghz machines gets a score of 56.67 (ATI 9000 video, 160GB IDE HD) while the 867 now gets 42.56 (Geforce 2 MX and the same 160GB IDE HD). I think the 800 got a score in the mid 20's.


Makes me wonder why Apple even bothered to make a QS 2001 with 733 no L3 cache and a QS 2002 with a 800 no L3 cache.

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Thats an excellent question. I know what you mean about speed too. My 867MHz TiBook is MUCH faster than the 867MHz 12" Powerbook I had even though the 12" had faster RAM and newer components all around. That L3 cache made a HUGE increase in performance.

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  • 2 weeks later...

I can confirm that L3 makes "all the difference". My son has a quicksilver (actually a DA logic board), overclocked to 150MHz FSB. The 1.5GB ram is running CAS2 at that speed, and GeForce 4 Ti graphics under OS9. I think this is pretty much the fastest possible setup.


For a long time, I was running a 7447 @ 1.5GHz (512k 1.5GHz L2, no L3) but I was still experiencing lag in a few of the more demanding SuperNintendo and Gameboy color games we play (Kirby and Shantae spring to mind). Anyway, I got tired of the fact that I couldn't sleep the machine no matter what combination of 3rd party enabler/multiprocessor plugin/energy saver settings I tried.


So I put in an older OWC 7455 clocked at 1.2GHz (150 x 8 ) with 2MB SDR L3. As expected, sleep now works great! However, what I didn't expect was how much faster the emulators were... It was night and day. Games which had been glitchy and dropping down to 45fps now run consistently at 60fps, flawlessly. I really didn't expect this because the L3 cache is running at 5:1, or 240MHz... That's only 1.5x the RAM speed (and CAS 2 dammit!).


Maybe OS/X is different, I don't know. As it stands though, for me in my ultimate-retro home-theatre (1360x768 37" : ) setup, a 7557 with L3 would be epic.

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I thought this had been said, but I'll go ahead and put this here: Each revision of the PowerMac G4, Apple had a cheap/crappy one, and by about halfway through (Especially with the no-cache Quicksilver 2002 models) it had been noted somewhere that the cheap/no-cache models were probably a nod toward the education users and home users who were not going to notice the difference.


Of course, eventually the eMac came out, but there's always someone there to remind me that sometimes you just /need/ the swappable graphics card, multiple hard disks and 3 PCI slots, even though you're buying a G4 with no cache, so I'm sure there are fringe situations where it was better to buy the tower with no cache than the eMac. [:P]]'>


Other situations I can think of are generic office tasks and situations where the computer had accidentally been bought by a home user instead of an iMac (or the later eMacs that were sold to consumers as well.)


Also, cache memory is the most expensive kind of memory, I would not be surprised if it actually shaved a bit more off the cost of the machine(s, all of them listed here) than we're giving Apple credit for.

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Some cache helps a lot, but after a specific amount adding more does very little.


If you look at PCI powermacs the CPU upgrades with 1MB cache are much faster then the ones with 512K cache, no cache would be slow as dirt (like the original 233 Wallstreet CPUs with nocache).

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