My machine is a home-brew system, but using a pcie3.0 x4 like you. OS is w7x64, CPU is i7-4970K, 32GB DDR3
My performance (R/W) is:
seq = 1473/1057
512K = 1092/1035
4k = 43/114
4k QD32 = 1038/986
Note that TSSDR use a virgin disk (mine has 50-odd GB of data on it), and likely follow their...