Trying to get 4k @ 60Hz working on Mac Pro 2013 6,1 in Bootcamp

YCbCr 4:4:4 not being able to show 4K 60Hz makes sense. This only showed up when using the HDMI out on the MP to the TV. I think the HDMI out is 1.4 and not 2.0. I didn't expect 4K 60Hz to work, but I was surprised at 2K 60Hz.

I did not notice anywhere in the Windows display setup to choose any version of RGB or YCbCr. It switched automatically.

There is a link under the display information for "Display adapter properties for Display 1". That first shows my AMD D700 which I can click "Properties" but it's just for the drivers which are up to date. There is a "list all modes" button on the bottom of the window that shows every screen resolution possible in a list. It goes [resolution size], True Color (32 bit), [refresh rate]. There's something like 80 different listings to choose from.

The monitor tab has "Generic PnP Monitor" and if I go into "Properties" it tells me that my drivers are already the best option for it.

The last tab is Color Management. There is an advanced option that opens a rather large menu window with sRGB profiles, but I don't think that has anything to do with refresh rate

I switched the NVMe drive out of the Mac Pro, and put the Apple blade SSD back in that is running macOS Monterey 12.7.6

Plugged the Thunderbolt 2 adapter in and hooked up the HDMI. I was able to choose 60Hz.

According to both the display tab in “About this Mac” as well as the info from the Samsung TV itself, I am currently running 3840 x 2160 4K @ 60Hz

This is frustrating. I am only running Windows on this. I’m keeping the Apple drive in case I need it for firmware stuff.

is there something in the bootcamp drivers I should be looking for? I installed everything from the boot camp USB I made prior to installing windows

The adapter brand is "Plugable" which has been brought up many times as the adapter to get. It's listed as Thunderbolt 2 to HDMI 2.0.

The HDMI 2.1 cable is "Highwings" rated at 8k 60hz, 4k 120hz and 48Gbps. It is an ULTRA certified cable.

The Samsung TU7000 TV has HDMI 2.0 inputs

Does it make a different which Bus or port I use for the Thunderbolt adapter? I have no other devices plugged into the Thunderbolt ports. I have a wireless mouse plugged into the first USB port.

The current cable I have is 6ft, and from what I've read, should be ok with 4K @60Hz. This is the cable I purchased: https://a.co/d/3XYgeJL

The adapter that I have is this one: https://a.co/d/3ENEJXW

I have contacted Samsung about my specific TV to confirm that it is capable of 4K @ 60Hz. I've reached out to the company that makes the adapter regarding the 2k limit and am waiting on their response.

Samsung suggested I contact Microsoft too, but I don't think it's a Windows 10 issue, and I'm not sure how helpful they will be since I'm using it on a Mac.

I'm not able to make any purchases at this time to try a shorter cable. I hope this isn't the issue, because the Mac Pro is on the left side of the TV and the HDMI connections are on the right. I can't put the MP on the right side of the TV

The plot thickens. I decided to test every single Thunderbolt port since it's unclear if one is better over the other. I tested 1920 x 1080, 2560 x 1440 (2K), and 3840 x 2160 (4K) resolutions

Here we go

HDMI using just the cable and no adapter:

1080 - Up to 60Hz, 12-bit depth, YCbCr444 color format. Also allowed interlaced at 50Hz, 59.940Hz and 60Hz

2K - Up to 60Hz (again, just the HDMI port on the MP), 8-bit depth, RGB color format for some reason

4K - Up to 30Hz, 8-bit depth, back to YCbCr444 color format

Each time I switched Thunderbolt ports, I disconnected the HDMI cable from the adapter and waited 10 seconds before plugging the adapter into the MP by itself, followed by connecting the HDMI cable. I only tested 1080 and 4K going forward

Thunderbolt Bus 1 Port 1

1080 - Up to 60Hz, 10-bit depth (down from HDMI only), RGB color format. Also allowed interlaced at 50Hz, 59.940Hz and 60Hz

4K - Up to 30Hz, 8-bit depth, RGB color format

Thunderbolt Bus 1 Port 3

1080 - Only options were 59.940Hz and 60Hz, 12-depth (back up for some reason), RGB color format

4K - Up to 30Hz, 8-bit depth, RGB color format

Thunderbolt Bus 2 Port 2

1080 - Up to 60Hz, 10-bit depth, RGB color format, Also allowed interlaced at 50Hz, 59.940Hz and 60Hz

4K - Up to 30Hz, 8-bit depth, RGB color format

Thunderbolt Bus 2 Port 4

1080 - Up to 60Hz, 10-bit depth, RGB color format, Also allowed interlaced at 50Hz, 59.940Hz and 60Hz

4K - Up to 30Hz, 8-bit depth, RGB color format

Thunderbolt Bus 0 Port 6

1080 - Up to 60Hz, 10-bit depth, RGB color format, Also allowed interlaced at 50Hz, 59.940Hz and 60Hz

4K - Up to 30Hz, 8-bit depth, RGB color format

Thunderbolt Bus 0 Port 5

1080 - Up to 60Hz, 10-bit depth, RGB color format, Also allowed interlaced at 50Hz, 59.940Hz and 60Hz

4K - Up to 30Hz, 8-bit depth, RGB color format

From what I see, it appears that Thunderbolt Bus 1 Port 3 is a bit different from the others. Not sure why 1080 was suddenly stuck at only 60Hz and why the bit depth changed from 10 to 12 on that port. This does tell me that the MP probably has a preferable port for the first and only monitor hookup.

I don't have a 120hz TV or monitor to test just the HDMI at 1080 at that rate. I am still waiting to hear back from the adapter manufacture.

I understand the age of the devices I play around with. Regardless of what Apple's plan was, this Mac Pro is capable of what I'm trying to do, I just haven't found the right combination to unlock it in Windows.

I enjoy older technology for both the challenge, and to keep things out of trash heeps if they can be useful. When I ask a question on here, I don't just sit back and wait for an answer. I'm constantly trying other things and updating what I've found. This is to both potentially come to an answer from someone who sees it, and to make sure there's a detailed thread for anyone in the future that runs into the same thing.

The slow clap for me getting it to work in Monterey doesn't help, and the issue of getting it to work in Bootcamp still remains. I'm going to keep at it.