Surprise in an LC 580

[jeaster33]

So, I just picked up an LC 580 (amongst other things) from a guy on Facebook Marketplace. He was not a computer guy and just found them in a home he was renovating, so not the original owner. Anyway, I opened up the LC today to upgrade RAM, swap out the struggling IDE hard drive and generally inspect everything. Outside of brittle plastic falling apart on me as I worked, I noticed that the motherboard looked different from the Apple manual I was following online for an "LC 580". After some confusion, I saw that I had a PowerPC 603e motherboard (820-0751 A) from a 5300/100 LC in there! Sure enough, the profiler shows the model as a "PM 5200/5300" and the processor as "PowerPC 603e running at 100MHz". It took the full 64MB of RAM (when the 580 is only supposed to handle 48) and it booted up to Mac OS 9.1 (which was on the HDD I had installed, planning for it not to read), much to my surprise.

My question is, even though this is a nice and unexpected upgrade, will it hold up over time? I read somewhere that a power mod needed to happen to make this work too. I assume whoever had this before me did that because it all seems to work (albeit, slowly) just fine. I think I'll go with Mac OS 8.1 or 8.5 eventually. Anyway, was this a common swap back in the day and can I use it as a "PM5300" as long as I don't use the PCI slot?

 

[jeremywork]

will it hold up over time? I read somewhere that a power mod needed to happen to make this work too. I assume whoever had this before me did that because it all seems to work (albeit, slowly) just fine. I think I'll go with Mac OS 8.1 or 8.5 eventually. Anyway, was this a common swap back in the day and can I use it as a "PM5300" as long as I don't use the PCI slot?

The bit about modifying the supply for PCI voltage is correct, but the 5300 is the final model before the switch to PCI. Yours should be perfectly compatible as far as I've heard. The 580/630/5200/6200/5300/6300(except the 6300/160MHz) are all share a board form factor and are equipped with an LC PDS slot instead of PCI.

 

[Byrd]

Nice find, it would be a straight swap, slide out old LC580 and slide in 5200 board. You'd need to hack up the back panel for PCI access. It can be considered slow for PPC standards but with some cheap upgrades (faster HD or SSD, more RAM) more capable than the LC580 board it replaced. I'd go both Mac OS 7.6 for speed and OS 8.1 for more modern feel.

 

[Phipli]

(when the 580 is only supposed to handle 48)

The 580 will take up to 196MB RAM, Apple used to quote the capacity based on simms available at launch. It will take one 64, one 128 plus onboard (which I think is 4MB??).

 

[Phipli]

You'd need to hack up the back panel for PCI access.

The 5200 didn't have PCI, they'll be fine