I have matched 16GiB sticks of G-skill Ripjaws V (F4-4266C17D-32GVKB) that are rated to run at 1.5V and 4266Mhz. In order to tighten my primary and secondary timings at 4011 Mhz on my z390 Asrock Taichi (a lousy motherboard for memory o'clocking) it's necessary to run this DDR4 at 1.52V (in the BIOS settings) which is indicated as actually being 1.544V in HWiNFO64 as well as in the BIOS readings. The maximum DIMM temps I've seen at this voltage were 40.3°C but the ambients are only ~73°F(22.8°C). Are these voltages problematic for these DIMMs? I believe these DIMMs are Samsung B-die.
As an interesting aside, in order to get these sticks to properly train at 4000+Mhz. it's necessary to manually specify the RTL Init and IOL Init to 65 and 4 respectively, otherwise the memory won't train at all. I once had the memory train on auto settings to 4118Mhz. but I've come across no combination of manual settings for RTL init and IOL init that has ever worked at this frequency.
As an interesting aside, in order to get these sticks to properly train at 4000+Mhz. it's necessary to manually specify the RTL Init and IOL Init to 65 and 4 respectively, otherwise the memory won't train at all. I once had the memory train on auto settings to 4118Mhz. but I've come across no combination of manual settings for RTL init and IOL init that has ever worked at this frequency.