I have tested the total NAND writes in OS win7 x64 newly installed with the all x64 drivers, the chrome cache is moved to HDD partition, and the result is same as the one in win8.1. when the Value of Host Writes improved only one, namely 1*32Mb total host writes, there are almost 2Gb added to the total NAND writes. Attached is the captured graph from which we could get the monitoring data and the disk activity.
Finally, I speculate that there is a bug in the Intel 530 SSD firmware, DC22, if nothing wrong is in the testing environment.
The beginning capture:
The final one:
