I work of a school system that has for the most part all Mac computers! I do all repairs on the computers. I am working on a eMac (USB 2.0) it has a bad HD and I have tried 3 different new 7200 RPM 80GB HDs with no luck.It came with a 5400 RPM 40GB HD. I was told buy one of our suppliers that there head Tec repair person said that you can only use a 5400 RPM HD in these. Is that true and if so where is a good place I can find these cause I can not find them at a reasonable price. If not how can I make it work in my computers?

The 7200 rpm drives should work great in an eMac. If the drives have been tested good, then I suspect something is amiss with the bus. How does it boot from CD?

I have not tried to boot from a CD we image all of our computers! I put the new 7200 RPM 80GB HD in to the computer and target booted it installed the image fine and then restarted it and it shows the "?" like it can not see the HD. I tried this with 3 new out of the box HDs. I then found a used 5400 RPM 40GB HD like what came out of the computer and installed it and imaged it the same as the others! This time it started fine and runs with no problem. My problem is I am having a hard time finding 5400 RPM HDs and I need to use the 7200 RPM HDs if I can get them to work some how.

Also I have tried to install this in 3 different eMacs that I think have the same problem " a bad HD" so i think I am on the right track but I'm not sure. I am learning to fix these on my own they are just coming out of the 3 year apple warranty and I am having to fix them as I learn!

I can't imagine why you couldn't use a 7200 drive. It does sound like the HD is in question of maybe your boot image has been corrupted?

You should try Option booting to see if the drive is available in the list, and has an OS X icon next to it.

You may want to check the formatting on the 7200 drives. Try Zeroing one out, and reformatting it as Mac OS Extended (Journaled). Then image over it, and try booting again. I've had issues with drives exactly how you're describing, and a Zero + Reformat = Success.

Good luck!

The thing I guess I really need to know is if for sure a eMac (USB 2.0) with a 1GHz pro. will will be able to use the 7200 RPM 80GB HD? All of the spec. sheets and info don't see anything about the speed of the HD. I can't find and good info either way. I know these HDs work fine in the newer eMac (2005) models we have. If it matters these are education eMacs they only sold the eMac (USB 2.0) with a 1GHz pro. to education buyers I have found that out looking up info on them.

try giving the guys at ifixit.com a call. They may be able to help you out with a 5400 RPM drive at a reasonable price. Tell them you heard about them from MacMod and they might even give you a discount.

There's no reason whatsoever that the 7200RPM drives won't work, unless it's a firmware issue. Systems normally don't bias against drive speed, only drive firmware. And even then, rarely. (I wrote an article about it... http://lowendmac.com/ed/herlihy/08ph/upgrade-options.html)

Try what I suggested on one of the drives, and report back.

http://discussions.apple.com/thread.jspa?messageID=6237789

No mention of eMacs biasing against drive speed.

http://lowendmac.com/imacs/emac-2004-1.25-ghz.html

This also affirms that 7200 RPM drives are compatible.

I'll put money it's your drives formatting. Follow what I suggested.

have made sure the hard drive was set as cable select or as a slave should set to cable select. I have a emac that I have upgraded to a 250 gig HD and works perfectly.