Disable HDCP regedit

Performance differences aside, being able to disable HDCP in Windows registry just saved me from having to replace my second monitor.

Many years ago on overclock.net and other enthusiast sites there was a minor online fervor over some cheap 1440p IPS monitors being sold on Ebay. Some entrepreneurial Koreans started dumpster-diving for discarded IPS and PLS panels from LG's and Samsung's factories, testing them for a maximum dead pixel count threshold, and placing them in the cheapest casings with no OSD hardware at all, then selling these super budget 1440p monitors online for like half as much as the actual LGs and Samsungs under spun-up brand names like "Qnix" and "X-star" and such. The overclocking community lost their collective crap over these monitors because on top of being affordable, the refresh rates were very overclockable.

Downside to these monitors is that, to keep them cheap, the sellers used the absolute most barebones hardware around the panel, including selection of inputs. Most monitors only had a single Dual-Link DVI input and nothing else. Dual-Link DVI isn't exactly a popular interface, and it's hard (or maybe impossible?) to find current generation GPU with a Dual-Link DVI output.

So having recently bought a RTX 3080 and a DisplayPort-to-Dual-Link DVI adapter, suddenly I'm finding that this old faithful Korean 1440p monitor "breaks" when watching HDCP content. The adapter is picked up by the GPU driver as a repeater and HDCP kicks on the DRM static. I was resigned to having to buy a new monitor to deal with this, until I found this thread. Disabling HDCP in Windows completely fixed the issue.

I understand the purpose and value HDCP provides to content owners, but it'd be nice if it didn't throw false positives. I understand that my unique hardware situation is probably representative of only 0.000001% of the world but nonetheless, it almost cost me money.

 

One-liner for HDCP disable:

Code:

reg add "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4d36e968-e325-11ce-bfc1-08002be10318}\0000" /v "RMHdcpKeyglobZero" /t "REG_DWORD" /d "1" /f

It expects the GPU Class Guid to be {4d36e968-e325-11ce-bfc1-08002be10318}


I don't play protected content and have no use for HDCP. I've heard in other places it causes extra latency for VR, and apparently Palmer (Oculus) said something along those lines too: https://forums.blurbusters.com/viewtopic.php?t=506

In any case, this registry option works fine with 516.63. NV control panel reports "This display does not support HDCP as configured."

I remember years ago where AMD's graphics drivers on Windows were forcing HPET, regardless if it was beneficial or not. I had no known issues while using HPET, but I saw discussion about it, disabled it, and noticed responsiveness improved notably. I tend not to blind-trust settings on Windows.

In Linux, I can clearly see TSC is being used by-default with all the CPUs I've dealt with so far, and the other day I had a Dell laptop that reported that HPET was bugged on that platform and was disabled automatically.

 

Is this registry setting supposed to work with AMD cards? I tried it and it seems it did nothing.
I'm asking because I don't have that HDCP toggle in Radeon Settings, so I'm looking for an alternative solution. (I have some display stuttering problems and disabling HDCP is a common remedy.)

Radeon Settings actually says that it's disabled, but I'm not convinced.
For example, when I run this test, it says "HDCP is available for 1.0":
https://googlechrome.github.io/samples/hdcp-detection/
Can someone else try it, just to see if it's even a good test for checking HDCP status? (Note: in Chrome it works by default, in Firefox you need to enable media.eme.hdcp-policy-check.enabled first.)