The Board is authorized to appoint custodians for the safekeeping and payment of retirement system assets. The selection of these investment services shall be governed exclusively by the fiduciary standard set forth in this chapter. The Board may request the State Treasurer to issue retirement benefit payments on behalf of the retirement system. At the direction of the Board, retirement payments from the accounts shall be made by the State Treasurer, on warrants of the Comptroller, issued upon vouchers signed by persons designated by the Board. A duly attested copy of a resolution of the Board designating the persons and bearing on its face the specimen signatures of the persons shall be filed with the Comptroller as his authority for issuing warrants upon such vouchers. No voucher shall be drawn unless it has been authorized by Board resolution.