Not really so much rise in T. Rather, boron catalyzes hydroxylation of T to dehydrotestosterone. T itself has no biological effect. Same with the estrogens, boron catalyzes hydroxylation of estrone to become estradiol, and then finally to estriol. Lack of boron means a buildup of estrone, the bad estrogen that's ascribed to causing cancers. So, its better to view boron or borate, as being a hydroxylation catalyst that converts T to its active form, and not so much as something that "increases T". Supplementing B may cause serum T to rise a little, but that's only because T is being taken out of the equilibrium by its hydroxylation to dehydroT.