I Bought: Patriot Viper Steel Series DDR4 16GB (2 x 8GB) 4400MHz Performance Memory Kit - PVS416G440C9K1) Supporting HW.2) What I achieved.4) Problems I encountered.5) How I did it.6) I will post back in one month to give my one month feedback.1) So first of all here is my "supporting" hardware:Asrock Z370 Extreme 4 Mother board. ("Capable of 4133+OC Ram")i7-8700k CPU OC @ 5Ghz2) Second here is what I was able to achieve:4000Mhz @ 15-15-15-35 CR2**With my "supporting" hardware**3) At first I couldn't get the ram to boot over 3000Mhz, like at all! But I did adjust timings to 12-12-12-32 CR2 @ 3000Mhz and probably could have gone lower on the timings!4) How I Managed to get it to run at 4000Mhz.**Please follow all of these steps to a T!!**If you skip any of these OR do them out of order it can result in damaging your hardware, My instructions are safe but please overclock at your own discretion...NOTE: I THINK ASROCK MOTHERBOARDS PRIMARY RAM SLOTS ARE A2 B2!!!I was unable to achieve 4000GHZ prior to trying this out.Try my guide first then try swapping ram to A2 B2 slots.1 - Reset CMOS to restore bios default, in my case I HAD to use the CMOS reset method.Simply resetting to default settings in the UEFI Bios menu **DID NOT WORK.**(NOTE: Sometimes the CMOS Battery is located behind the Graphics card.)This will require you to power off your pc so save this review in a screenshot on your phone.Once you have successfully reset the CMOS and have default Bios proceed to step (2)***DON'T OVERCLOCK YOUR CPU FIRST! START WITH THE RAM!***2 - Set BLK frequency to 100 if it is not already set to 100.Make sure you're in DRAM settings and not CPU settings.If BLK frequency says 45, 43, 48, 37, or 50 you're in CPU settings...They should be linked but you need to be in DRAM settings.3 - Start at 4000Mhz for speed, set DRAM speed or "frequency" to "4000" or 4000Mhz, whatever option it gives you start at 4000Mhz if you do not see 4000 as an option but see odd numbers like 4016 it's because your BLK frequency is set over or under 100.00.4 - Set ALL other DRAM settings to "Auto"! If they aren't already? Manually type in "Auto"**********This is the most important step in order to keep things from going poof or zap.********************This is the most important step in order to keep things from going poof or zap.********************This is the most important step in order to keep things from going poof or zap.**********5 - THE MOST IMPORTANT STEPFind voltage settings, (May be in CPU settings etc just find VCCSA VCCIO voltage settings)Set DRAM Voltage to 1.35, UNLESS you have an XMP profile that says it uses 1.45If you see an XMP profile that says it uses 1.45 then Set the DRAM voltage to 1.45 this will be safe.MAKE SURE VCCSA Voltage settings are set to 1.15~1.30 **NOT SET TO AUTO**To Start, Set to VCCSA to (1.2)SET System agent voltage 1.10V~1.35V Start at 1.2MAKE SURE VCCIO Voltage settings are set to 1.15~1.30 **NOT SET TO AUTO**To Start, Set to VCCIO to (1.2)Navigate to "exit", -> Save changes -> and reset.**IF** it boots to windows and runs congratulations you have a starting point at 4000Ghz. Proceed to step (W)**IF it doesn't boot, blue screens, crashes, or enters vicious boot loop, enter bios for adjustments. Proceed to step (X)**IF** you are unsuccessful at entering bios, power down machine and repeat steps 1-4. Then Proceed to step (X) before saving and resetting.STEP X: You can try increasing DRAM voltage from 1.35 to 1.4.You can try increasing VCCSA, VCCIO, System agent voltage to 1.25, if this fails you can attempt 1.3 if that fails, You need to lower the DRAM Frequency from 4000 to 3800 and repeat until you have a starting point.STEP W: Ok, we have a starting point, now we can adjust our timings!**IF** you had instant success at hitting 4000Ghz, set your timings to 15-15-15-35 CR2 And attempt boot.If this works, lower until it is unsuccessful at boot and revert back to the lowest successful post.Fine tune for stability and run tests to ensure your configuration is successful.Now you can overclock your cpu.**ELSE**Start by setting your timings to 19-19-19-39 CR2 And attempt boot.If this works, lower until it is unsuccessful at boot and revert back to the lowest successful post.Fine tune for stability and run tests to ensure your configuration is successful.Now you can overclock your cpu.If this doesn't work Revert back to "Auto" in all the timing settings, boot into windows, install CPU-Z from CPUIDNavigate to the -> memory tab and write down values for:CAS# latency (CL)RAS# to CAS# delay (tRCD)RAS# Precharge (tRP)Cycle Time (tRAS)Row Refresh Cycle Time (tRFC)This is your starting point.Extra info:VCCSA, VCCIO, increase to 1.3 MAX (1.35 for the F it folks)1.5 is Max capable for VCCSA, VCCIO but seriously don't go past 1.3.for fine tuning set a lower Command Rate (CR) 440 for example, research and fine tune the other settings you have available to you!