I'm not sure where you saw the tRFC is 36, unless a user referenced their timings?
As for adjusting, you can adjust the tRFC in your BIOS just like the rest of your timings.
In CPU-Z, under the "SPD", in the timing table under the XPM-1600, it gives the timing for it. I changed my DRAM settings for XMP under the bios and that is the timing I got. I was wondering what the tRFC is called in the bios. Thanks!