garageCube

[Lumenarius]

Long time MadMapper user here (15 years, since the Mac only days). I am about to order a dedicated Windows server for projection mapping and hit a question I want answered before I spend the money. Posting here so it is searchable for the next person too.

The build:
- AMD Threadripper 9970X on a TRX50 board
- NVIDIA RTX PRO 6000 Blackwell Max-Q (4x DisplayPort)
- Windows 11
- MadMapper 5 & 6

The goal: all 4 outputs on the 6000 go to projectors (4x 4K60, or 16x HD through Datapath FX4 splitters).

The problem: Threadripper has no integrated graphics, so the motherboard has no video output for a desktop monitor. If the GUI monitor takes one port on the 6000 I am down to 3 projector outputs. The obvious fix is a second small NVIDIA RTX PRO card (RTX PRO 2000 or A1000) that drives only the desktop monitor, with every app pinned to the 6000.

The catch is in the MadMapper 6 troubleshooting docs under Multiple GPUs (Windows):

"If you do have multiple GPUs, be sure to set the Main Display of Windows Display settings to a screen connected on the most powerful GPU. MadMapper will do all the processing on the GPU attached to the main display. When we'll switch from OpenGL to Direct3D on Windows, multiple GPU support will be improved, although we can't say when this will be ready."

So as I read it, if the desktop monitor on the small card is the Windows Main Display, MadMapper renders on the small card. Wrong GPU.

Questions:

1. Does processing follow the Windows Main Display even if the MadMapper window itself is sitting on the second card's monitor? In other words, can I set Main Display to a 6000 output, keep the GUI on the small card's screen, and have MadMapper render on the 6000?

2. Is there any way in MadMapper 6 to choose the render GPU explicitly instead of it following the Main Display?

3. Has anyone run this two card layout on Windows in practice, GUI on the small card and fullscreen output on all 4 ports of the big card? Did it work, and were there any surprises?

Trade-offs I already see, for anyone reading this later:
- If Main Display has to be on the 6000, that means Main Display is the projector Mosaic surface. New windows open there by default, so you need a way to pull hidden windows back to the GUI screen (Win + Shift + Arrow works if Snap is enabled).
- If none of this works, the fallback is 3 projector outputs plus the desktop on the 4th. Not the end of the world but it costs a 4K output on a very expensive card.
- The docs say multi GPU handling will improve after a move to Direct3D, with no date given.

If anyone from the MadMapper team or anyone who has built a rig like this can chime in I would really appreciate it. I will post back with results once the machine is here and tested either way.

Thanks,

[MatteLe]

In my understanding, you could use the interface on the pro 6000 and do ALL outputs on a smaller card (not sure if all outputs are framesync on the workstation cards, could be). At least I used this poor mans constellation with one rtx a4000 and some p2200 for having some edid locked outputs (but only poor wuxgas). The bus speed on pcie 5.0 is more than high enough for 4x4k60fps.

[mad-matt]

Hi,

MadMapper 6 is still OpenGL based (we'll soon be native Direct3D/Metal). With OpenGL it's very hard to choose the GPU. Same with other OpenGL apps (ie Resolume etc.). It will start on the GPU the main display is attached to. You can set one of your projector output to be the main display (but the windows login menu might appear there then which might be annoying in some situations)

If you just drive 4 video projectors at 1080p resolution, I advise you to use a video splitter like Datapath FX4 or cheaper alternatives (Matrox QuadHead2Go, Startech thing...) to send a 4k60 stream from one of your video card output and split it into 4x 1080p60 outputs. Then you run everything on a single GPU and avoid memory transfers from a GPU to another. Best is to try, with today's computer we have lot of bandwidth so memory transfers from a GPU to another might not be a problem.