The timings on G.SKILL's 4GHz DDR4 is 19-21-21-41, assuming you can find a chip and chipset which supports it.  For TechPowerUp that is an ASUS TUF Z370 PLUS GAMING and a Core i5-8400 @ 4.0 GHz.  The tight timings on the kit help it during benchmarking, and at roughly $245 for 16GB it is not the worst deal out there.  As an added benefit for some, the kit lacks any RGBs whatsoever!

"The G.SKILL Trident Z sticks have been around for a while now, available in a multitude of colors and speeds, as well as with RGB. These 4000 MHz sticks are for all you non-RGB lovers out there, but with such a high speed, you best make sure your motherboard and CPU are capable."

Here are some more Memory articles from around the web:

Memory