35 minutes is generally a semi decent indication of stability so it does seem like temperature is your problem. If you can make it to the second cycle starting (~1 hour) that will be okay too. Last month I was stress testing a CPU for 90 straight hours so 3 hours is nothing to me.
What you should be doing is the following (if it is temp related): Run the standard XMP 14-15-15-35 but at a lower voltage like 1.40v. Kits of this caliber have ridiculous headroom to lower voltage. I've seen them run xmp profile at 1.37v before.
Lowering voltage might take like 3-4c off your peak temps that it will then be stable. If you still crash then yeah try something ridiculously lower like 16-16-16-36 at 1.35v. If you still have crashes at 1.35v something is horribly wrong with cooling or the RAM is just bad.