Upgrading iPXE booting Windows 7 to Windows 10

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Hi,
I've been working on this for weeks, I deployed diskless desktop computers successfully in company months ago by cloning local installed OS to iSCSI LUN, hosting about 30 computers. Everything works fine until Microsoft release cumulative update for Windows 10 version 1607. Computers which have version 1511 installed download the update and keep trying to update to 1607. But the "Cumulative Update" requires a WinPE environment to install(I guess), then the update failed and leaving the computer "preparing for automatic repair".
Now I'm considering two solutions:
1. Deploy Windows 10 Version 1607 again and pray. Microsoft may solve this problem in version 1607, so the next cumulative update will success without problem.
2. Buy a iSCSI HBA card for every computer. I have even chosen a model QLE4060c form QLogic. Buying a used card is cheap form taobao.com(similar with eBay). The HBAs card will connect to iSCSI target and emulate a local storage device for booting operating system, block I/O etc. It work just like a local drive.

Any suggestions?