• Beige (Platinum) G3s - the first models (so called rev A/rev 1 - see the FAQ for how to check this) do not support more than one drive per IDE cable. Personally due to potential issues I noted in my 1998 Beige G3 MT drive upgrade guide (where to mount the drive so the 6" master/slave cable spacing will reach, etc.), if you're still running the original 4GB drive, that's no big loss when you can get a 40GB drive for under $100 now (as of 2002) and copy your data to it. (See the guide for a tip on using the CDROM cable temporarily to do this). Another simple option is to replace the IDE CDROM drive with a hard drive and use a SCSI CDROM drive in its place. If your Beige G3 has an IDE ZIP drive, it's a rev B or later model (since the IDE ZIP is a slave drive, the CDROM always ships set to master.)
  
  
• B&W G3 Revision 1 - as many readers unfortunately already know (and has been reported here ad nauseum since about spring 1999), the IDE chip revision on the rev 1 B&W G3 motherboards doesn't like slave drives or even many modern replacement drives run as Master alone. (See the drive database for reports, the FAQ for a data corruption tester and the rev 2 features page for how to check your IDE chip to see if it's the revised one.) If you have a B&W G3 with a rev 1 IDE chip on the motherboard, a PCI IDE controller card is the safest and best way to upgrade/add additional drives. See the IDE articles page here for more info and remember the comments above on OS X compatibility with certain brands.
  If you have a B&W G3 rev 2 (or at least the revised motherboard IDE chip), then you can easily add a 2nd (slave) drive or replace the original drive using the onboard IDE controller. See the IDE articles page here for guides w/photos, etc.
  
  
• G4/PCI and G4/AGP Towers all shipped with a dual drive cable and stacked drive bracket to make adding a 2nd drive easy. See the IDE articles page for the guide to adding a 2nd drive.
  
  
• G4 Cube - Apple has a PDF file and Quicktime movie on replacing the hard drive at their G4 Cube Customer Installable Parts (CIP) page. They do not cover jumper settings but most IDE drives ship set to master as noted in the other mac articles here. (But check the settings on the label to verify this before installing the drive.)
  
  
• iMacs - The drive database here has some owner comments that might be of help, but the iMac DV (slot loading) off-site article linked in the FAQ's iMac/iBook section vanished. With the iMac, beware the CRT assembly stores hazardous voltages even with power disconnected, so officially I'd suggest a qualified person perform any HD upgrades in those models (although I and many readers posting in the database have done it.)
  
  
• iBooks - perhaps the most difficult Mac to upgrade the internal hard drive due to an almost complete disassembly of the computer being required. The FAQ noted a reader's guide and PDF file, but those also vanished from the web, although I may have saved the PDF file and if I can get the author's permission I'll mirror it. As noted in the FAQ - even the 2001 iBook has a max drive height of 9.5MM. (The largest 9.5mm high drive I'm aware of is 30GB.)
  
  
• Powerbook G3 Series - Guides to 1998 Wallstreets (G3/233-300Mhz) and 2000 Pismo (G3/400-G3/500 Firewire) models are linked here on the IDE and Systems page (PB section). The 1999 Lombard (G3/333 and 400mhz w/no onboard firewire) case is practically identical to the Pismo so that guide should be of use. For the G3/333 Mhz and up Powerbooks, a 12.5mm high drive is the max height drive you can use inside. The 1998 wallstreet series (G3/233 to 300mhz) can accept up to a 17.5mm high drive. This is not as big an issue now as in the past, as drives as large as 48GB (44.7GB formatted) are available from IBM with a drive height of only 12.5mm.

• Is the small size of the portable drive and lack of AC adapter important to you? (do you travel a lot, or need to carry the drive between work areas to use with many different computers?)
  
  
• Do you have a spare drive already? (If you do the type of drive - notebook or desktop - dictates the case type/size.)
  
  
• If you need the largest FW drive possible, then the 3.5"/AC powered cases mean you can use lower cost per GB drives and have a much wider selection (and sources) of them. 2.5" notebook drives have come down to where a 20GB notebook drive is close (within $50 often times) to the cost of a 20GB desktop drive depending on where you buy it, but at sizes of 30GB and larger, the desktop drives are usually many times cheaper. And 48GB is currently the largest notebook drive on the market. (It's more than twice the cost of many 60GB desktop drives also.)
  
  If you own a desktop Mac, another consideration is that should the Firewire case fail, with an AC powered/3.5" drive case, you could remove the drive from the case and install it in your desktop Mac. (Assuming the case controller/AC adapter failed and not the drive itself of course.)
  
  
• If you don't already have a spare drive or would rather not assemble a case kit (see the guides here on case kits - it's not hard to do), then buying a completed drive may be a better fit for you. Many "name brand" complete FW drives contain unknown (and varying) drives inside - which could change at any time, so consider this when reading past reports on "name brand" drives. (Maxtor or WD are exceptions, as they of course use their own brands of drives and spec the drive on the box pretty well). Until recently however, the WD/Maxtor drives did not use the faster FW bridges and they usually cost more than either kit builds or buying a completed drive from a vendor that also sells cases. (Often the dealer of cases will offer assembled drives of various sizes, etc.) In some cases you may even get a better deal from a prebuilt kit that you can buying the case + drive separately.
  Building the case kit yourself however is satisfying (in my opinion) and you'll know how to replace the drive in the future should you want to do so (upgrade it to a larger IDE drive, etc. as prices drop/sizes grow as they always do.)
  
  
• Some Firewire drive cases from "name brand" dealers (ie VST) are not designed to have the drives inside easily replaced. (However I did post a guide to how I replaced the 3GB drive in my VST ultraslim case with a larger one - see the hard drives section of the Firewire articles page for a link.) Although anything is possible with enough skill, care and determination, the case kits or drives from case kit vendors are usually easier to upgrade with larger drives later. (Note many earlier VST ultraslim drive housings will only fit 9.5mm high max drives - later cases or those that shipped with higher capacity drives are taller for 12.5mm drive compatibility.)
  
  
• Firewire Drive/Case Noise: Portable Firewire drives are almost always quieter than 3.5"/AC powered drives. All drives make some noise, especially when the drives are accessing data (head movement), although most I have used are not really noticable while you're working. Many 3.5"/AC powered cases now have no fan in the case and depending on the drive inside, are very quiet in my opinion (far quieter than any Tower Mac). Some cases (most all that are sized for CD size drives) have a fan however. (My OWC Elite case with IBM 60GB drive has no fan as noted in that review/build guide, and seems as quiet as the Cube with Radeon card.)
  
  
• If you shop around at the dealers selling case kits, you'll see many similar cases being sold. If the specs are the same (if it has the faster Oxford 911 bridge board, the dealer will usually note it) then there's basically no difference in them except for perhaps the firmware of the bridge board. Since most buy from the same OEM (original equipment manufacturer) source, it's likely that currently stocked cases with the same bridge board have the same firmware. What may vary is the type/brand of driver CD supplied - but as noted in articles here, I format my drives in the Finder usually for maximium compatibility. If you build the case with a new drive yourself, plugging it in the Mac firewire port will usually have the Finder pop up a dialog allowing you to initialize it. If you buy a pre-assembled drive, it could have been formatted using Radialogic or other drivers.

The Frequently Asked Questions area here is topic/systems based also and may be of help.

Performance tests and comparisons of drives are also linked on the IDE, Firewire and SCSI articles pages here. (See the topics links under the logo above and at the bottom of this page.) The articles usually have links to sources and pricing, but remember prices can change daily, so check for the latest pricing. For IDE internal hard drives, often local retailers may have good prices or special offers. (I've seen some really good deals here at Sam's Club and sometimes at Costco - but stock changes often and the really good deals don't seem to last long.)

I know most of this is nothing new to many of you and I can't cover everything or every option, but for less experienced users that are torn between firewire or internal drive upgrades, portable vs AC powered, etc., I hope the above comments and links are of some help.