If the "DSP card not ready" error happened intermittently and got worse over time, then you probably have an issue with something making intermittent contact, somewhere.
If you're lucky, then re-seating the cable(s) as mentioned in my last post might be enough (I'd really clean the contacts with electronics cleaner or isopropyl alcohol while you're at it, though). Probably best to do that on both ends, though.
Trying a different cable would also be worthwhile, if you can find one easily.
Since you say the problem was intermittent, if reseating the stuff "outside" the rack unit and console doesn't work, it's probably time to open the console and re-seat all of the ribbon cables, and clean them while you're at it (and Phil C. on here always recommends to lift off the plastic parts where the connectors on the ribbon cable pierce through the cable itself (but don't remove it... just so there's enough of a gap), then put some alcohol in there, and then clamp the connectors back together... and I agree... if you already have the console open, this would be a good idea to do).
As far as the BIOS goes, I'm not suggesting to flash the bios at all. Just open the BIOS (depending on the mainboard, you repeatedly hit the delete key, or the F1 key on your keyboard right after you power on, to get into the BIOS), and then manually change the settings to what it says in the database is right for your mainboard model. This is ALWAYS a manual process, and even if you'd flash the BIOS with an updated version or something, you'd STILL have to set the settings where they'd need to be.
Flashing the BIOS is like replacing it completely. I'm just suggesting to double-check the settings and change them if they're not right.
If the desk intermittently worked, and every now and then gave the DSP card error in the past, it's unlikely that it's the BIOS settings, though. It never hurts to check, though, as this is comparatively VERY simple to do, but can have serious implications if something's not right.
Anyway... just thought I'd respond so you don't try to flash the BIOS. That could brick the mainboard if making a mistake. Everything I said in my last post still applies and I'd still start with re-seating the cable(s) on the outside of the console and rack unit first.
If that doesn't work, I'd open the console and reseat/clean all the ribbon cables.
It's a very common thing people have to do with their D8Bs every so many years. I had to do it to each of the ones I bought (used) as well, before I could really use them as intended and without strange and mysterious issues happening all the time. It might just be time to do that for yours. For the D8B, that's kinda "standard maintenance"