How can I set my RAM to its rated 3200MHz speed if my BIOS doesn't have an auto XMP toggle?

You can manually enter the XMP timings, voltage, and frequency in your BIOS. Go to the “Advanced” or “OC” section and set DRAM Frequency to 3200MHz, DRAM Voltage to 1.35V (for DDR4), and the primary timings (e.g., 16-18-18-38) from your kit’s label or manufacturer’s product page. Save and reboot; if it fails, clear CMOS and try 1.36V or looser timings.