Emachine IDE Add 2nd Drive - machine stops upon BIOS/Boot Logo Screen

If this machine is from the early 2000's, it is entirely possible that its BIOS does not include a feature called "48-bit LBA Support" on its IDE ports. The original "LBA Support" or "Support for Large Hard Drives" was a 28-bit version. That allowed HDD's to be up to 137 GB by manufacturer's way of counting (128 GB in Windows' way). I note that your old HDD was less than that, so there should have been no problem before, and there was not.

Now, however, the BIOS may be unable to get a "sensible" response (that is, one it can understand) when interrogating the 500 GB unit at POST time. It cannot understand HDD parameters too big for its knowledge. There MAY be a way to solve this. Check whether there is a newer version of the BIOS for your exact machine that can be downloaded and used to update your machine's BIOS - that is, a BIOS Update that DOES include "Support for 48-bit LBA". If you can do that, your machine should be able to deal with that HDD.

There is another solution, although less attractive. If you mount the 500 GB unit in a newer machine and download the Seagate utility Seatools. There should be a tool in there that allows you to tell the HDD to limit itself to only 137 GB. This tool will set a parameter in the HDD's on-board chips so that it always behaves this way and tells the outside world (including an old BIOS) that is its size. And that is ALL the space you can use on it that way - NOT the full 500 GB. (At some future time if you need it, there is a similar tool to tell the HDD to revert to its full size.) To use this tool, you actually tell the HDD the maximum NUMBER of Sectors it should have. That number is 2^28, or 268,435,456. To see what this gets you, remember that a Sector contains 512 bytes, so the capacity thus limited would be 137,438,953,472 bytes - aka 137 GB.

I knew I had this limit with an old machine I had that needed replacement HDD. Its problem was that I could not get an updated BIOS with 48-bit LBA Support, so I had to live with the 137 GB limit. I bought a 160 GB HDD and use the Seatools tool to set the limit, and it works just fine.