OK, I see how it is.
That second card... It's a 16GB? Since it crashes, something is wrong with the partition and formatting. The one that does boot (I'm assuming it too is a CF), you can put into a CF to IDE Adapter into the 5300 and it will boot it from the IDE. You will need a single CF to IDE Adapter as Dual CF to IDE do not work on Macs at all. See from the "Booting From CF Thread":
https://68kmla.org/forums/index.php?/topic/23406-booting-from-a-compact-flash-drive/&do=findComment&comment=243936
When the 5300 boots from the CF in the IDE, you can put in that faulty CF into the PCMCIA and repartition it and reformat it from there.
Those CF to IDE adapters you can get from ebay for a couple dollars - no more than $5 with free shipping. And only the Single CF Adapters will work on a Mac, the Dual CF Adapters wont. The Dual CF Adapters will work on a PC however... The only problem with these adapters is that they literally hang around inside the machine. You can use tape and thin pieces of foam to make a case that wraps around it that makes it rest properly inside the machine.
While on ebay, you can also look into CF cards and PATA SSDs. Maybe it's seasonal but lately I have been seeing prices drop lately.
Good luck.
That second card... It's a 16GB? Since it crashes, something is wrong with the partition and formatting. The one that does boot (I'm assuming it too is a CF), you can put into a CF to IDE Adapter into the 5300 and it will boot it from the IDE. You will need a single CF to IDE Adapter as Dual CF to IDE do not work on Macs at all. See from the "Booting From CF Thread":
https://68kmla.org/forums/index.php?/topic/23406-booting-from-a-compact-flash-drive/&do=findComment&comment=243936
When the 5300 boots from the CF in the IDE, you can put in that faulty CF into the PCMCIA and repartition it and reformat it from there.
Those CF to IDE adapters you can get from ebay for a couple dollars - no more than $5 with free shipping. And only the Single CF Adapters will work on a Mac, the Dual CF Adapters wont. The Dual CF Adapters will work on a PC however... The only problem with these adapters is that they literally hang around inside the machine. You can use tape and thin pieces of foam to make a case that wraps around it that makes it rest properly inside the machine.
While on ebay, you can also look into CF cards and PATA SSDs. Maybe it's seasonal but lately I have been seeing prices drop lately.
Good luck.