Which EPYC processors does the H12SSL-CT support?

It uses the SP3 socket and supports AMD EPYC 7002 and 7003 series processors. Check Supermicro's CPU support list for the exact model and BIOS version before buying.

How much memory can it take?

It has eight DDR4 DIMM slots, one per memory channel on a single EPYC socket. Registered ECC DDR4 modules are the intended type; capacity depends on the modules and CPU used.

Is it ATX or a proprietary form factor?

It is an ATX board, so it fits many standard ATX cases. EPYC coolers and airflow still need to be planned for a server workload.

Does it have remote management?

Yes, it includes Supermicro IPMI/BMC management, so you can monitor and control the server remotely. That is a key reason it is popular for homelabs.

How does it compare with a dual-socket board?

It gives one EPYC socket with full eight-channel memory and PCIe 4.0, which is enough for most storage and virtualization builds. Dual-socket boards add a second CPU but cost more and use more power.

What storage connections does it offer?

It provides a large number of SATA ports plus NVMe support through M.2 and PCIe, aimed at storage-heavy servers. Confirm the exact port layout in Supermicro's manual for your revision.