I thought I'd go ahead and start writing this up for the interest of folks here. I've always loved the B&W case design, and currently have three of them. One is a 350mhz model, and was given to me by its original owner, It is near perfect, has the matching CRT display, and all of the included original accessories. I did max the RAM in this one to 1gb, changed out the dead CD-ROM drive for a combo drive(CD-RW and DVD-ROM), and installed Tiger(as well as upgraded from 8.5.5. to 9.2.2) but have otherwise left it as-received. It's primarily an OS 9 machine for me. I have two "rougher" examples that came out of a lot of G3 and G4 towers that I bought a few months back(some of you may remember this). Both of these were 400mhz models(I had it in my head that they were 450, but was wrong). Both had various issues and were missing video cards, but both chimed and I was able to get both to boot completely. Here's my intended "victim" before doing any work(another member here sent me a drive bezel a while back in trade for some other parts-I will install it at the end of this project). A few weeks back, Gavin Stubbs listed a 450mhz G4 ZIF and a PCI Radeon 9200 in the for sale section for a very reasonable price. I jumped on them, with the mind to upgrade one of my "junker" B&Ws. Ultimately, I'd like to get Leopard working on this system, although I do have some other motivation. I have a computation chemistry program that I run occasionally which requires an ADB hardware key to work. The B&W is the newest computer on which I can run this program, as it was the last computer Apple made with a physical ADB port(the USB-ADB adapters DO NOT work for hardware keys). I don't think that the program will actually benefit from a G4 processor(it will run on a 603 or 604 processor), but should benefit from the faster clock speeds as well as the faster system bus of a B&W compared to older computers. I thought I'd write it up here for the interested folks. The parts arrived safely. The instructions Gavin gave me were to run the install disk under OS 9 before installing the G4 processor. As I understand it, one of the firmware updates(that was done as part of installing OS 9 on these B&Ws) "locked" the ROM so that they didn't recognize G4 processors. The disk "unlocks" the ROM so that a G4 will work to its full capability. I ran the program, and it instructed me to reboot while holding the "programmer" button on the front of the computer. Once this was done, I was able to run the software again and "unlock" the computer. Before proceeding any further, I thought it best to go ahead and install the drivers for the 9200. It worked perfectly under OS 9.0, but the drivers required 9.2.2. So, I proceeded through the upgrade path to install 9.2.2(9.0-->9.1-->9.2.1-->9.2.2). Unfortunately, after upgrading from 9.1 to 9.2.1, I found that the computer would lock up immediately upon loading the desktop. I had seen this problem before when fitting a Radeon 9000 into someone else's DA G4. The problem is related to not having the appropriate video card drivers(although I'm not sure why it worked fine in 9.0 and 9.1). In any case, the solution was to reinstall a Rage 128, proceed with the upgrade to 9.2.2, and then install the Radeon 9200 drivers. Finally, the Radeon 9200 could be safely reinstalled. I was finally able to get the 9200 drivers installed With that done, I proceeded to installing the G4 upgrade. The first step was to remove the heatsink. A single screw needs to be removed from the grounding strap, and then the clamp "unsnapped" to lift the heatsink directly off the processor. I'll take a moment to point out that this G3 is a "Revision B" model. The heatsink on these is larger than on the Revision A models. I'd encourage anyone considering such an upgrade and intending to keep the stock heatsink to start with a Rev. B model(or use a Rev. B heatsink) for the upgrade. I may end adding a fan, but for the time being the stock heatsink keeps things relatively cool. The thermal pad has long hardened into a solid lump, so the first step was to clean the heatsink. I use a combination of solvents-both Naptha and 91% isopropyl alcohol-to clean the heatsink. I've found that the naptha does a better job of cleaning off the bulk of the thermal material, while the alcohol is really needed to clean off the remaining adhesive. I also found a razor blade useful to get the semi-solid thermal pad off. I used a double edge, since that's what I had a surplus of(I actually shave with the things), but I'd suggest a single edge as probably an overall safer choice-otherwise just be very careful where you hold it. Here's the clean heatsink. I then removed the G3(750) and dropped the G4(7400) into the socket. Gavin told me that he had cleaned the processor before shipping it. Even so, I took the chance to clean it again using 91% isopropyl alcohol. This was to ensure a completely clean and(hopefully) dust free surface before applying fresh thermal paste. I used a series of cotton swabs, and kept at it until they came off completely clean. I used an additional clean, dry swap to wipe as much alcohol as possible off, then gave it a couple of minutes to dry. The next step was to apply thermal paste. There are no end of debates about how to do this correctly, but at least on these PPC processors with no IHS, I've settled on the "line and spread with a card" method. An old credit card/gift card is probably ideal for this, but since I didn't have a clean one I used an empty pistol primer tray which has a straight edge and is straight plastic. Artic Silver 5 is my paste of choice. Again, this can probably be debated to the end of time, but there's no question that AS5 is a good paste and has the added advantage of the fact that I can walk into Radio Shack and pick it up. I applied a line on the end of the processor And spread the paste. This is probably not the neatest job, but should get the job done I then re-installed the heatsink Upon booting, the computer promptly registered a G4 processor at 400mhz The processor is set as a multiple of the bus speed by a series of jumpers on the logic board. G3s have a small block that sets all of these settings under a "warranty void if removed" sticker. Considering that the computer is now approaching 16 years old, I think I can safely disregard this Removing the block reveals a series of jumpers conveniently marked "speed control." Apple supplied pre-made color coded all in one jumper blocks for the various speed processors these shipped with. I need a yellow block for a 450mhz processor, which I don't have. These jumpers are "mini" 2mm jumpers, not the standard desktop hard drive 2.5mm jumpers. I have lots and lots of 2.5mm jumpers, but am a bit short on 2mm jumpers. Since these are also often used on SCSI drives, I bit the bullet and ordered 100 of them off Ebay. It was only a few dollars more expensive than buying 10, and I figured I'd use more than 10 eventually http://www.ebay.com/itm/350557475053?_trksid=p2059210.m2749.l2649&ssPageName=STRK:MEBIDX:IT (no connection with seller). For the time being, I reinstalled the 400mhz block and am running the processor underclocked a little bit at 400mhz. The 400mhz G3 is going to make its way into one of my Beige desktops, so I'll need to play with the jumpers there too. By the way, even though I'm running 133mhz RAM, and the B&W board can theoretically support a 120mhz bus speed, I've been advised to NOT mess with the bus speed as it can cause all kinds of problems. I went ahead and installed Tiger. I've been playing with a Leopard install, but have been unsuccessful so far. I used my DLSD Powerbook to install Leopard in an external Firewire enclosure. I then booted off that install in the DLSD and ran the Radeon 9200 drivers. Unfortunately, that install kernel panics when the hard drive is transferred over to the B&W. I installed a DVD drive in the B&W and tried to use Leopard assist, but the B&W refuses to boot off the DVD drive with the Leopard disk in it(I even dug out my original, pressed disk rather than the burned "working copy" I usually use). I tried to install on a Sawtooth(Radeon 8500 installed, not the stock Rage 128) since I figured it was the closest G4 I have to this Yosemite using Leopard Assist, but the Sawtooth kernel panics on booting the installer(I do have a working install of Leopard on the Sawtooth-maybe I should just clone that). Unfortunately, since the B&W doesn't support TDM, I can't use that route with my TiBook or some other Leopard-supporting machine. I may also try using the external FW enclosure with my iBook G4, as it has the mobile version of the Radeon 9200. I'd appreciate any further advice on how to get Leopard on this computer. I'll also add that it currently has 868mb of RAM, and will soon be maxed at 1gb, Aside from that, I mostly wanted to write up what I'd done so far for the general interest of the folks here. I realize this is nothing ground breaking, but it is fun for me to make this sort of stuff work.