Descriptive Problem Summary:
Hardware rendering fails for certain users unless they install the directx SDK.

Because you presumably have it installed on your build/dev environment, such issues wouldn't be noticeable. (you could look at duel booting to a production environment that has none of that installed, or use your old computer since you recently got a new one.)

(note: the specified version is just the example i was able to find in our forums of somebody experiencing a rendering issue that was resolved by installing the sdk, no idea if its beta only, but no reason to suspect so because we've had this issue before with 510)

Note, users who play a lot of pc games rarely hit this issue, so it's more likely that some dependency isn't getting installed in the bundled directx thingy in the installer.