$ lspci -vmmnnk | grep "GTX 780" -B 2 -A 6
Class:	VGA compatible controller [0300]
Vendor:	NVIDIA Corporation [10de]
Device:	GK110B [GeForce GTX 780 Ti] [100a]
SVendor:	NVIDIA Corporation [10de]
SDevice:	Device [1051]
Rev:	a1
ProgIf:	00
Driver:	nouveau
Module:	nouveau

With a UHD monitor at 2560x1440 resolution with a High Speed-rated HDMI cable, it provided 59.95 Hz. At first, with a v. 1.3 DisplayPort cable, it provided a choice of 74.97 Hz or 59.95 Hz. However, after trying the higher frequency, which worked at first, DisplayPort stopped outputting signal on the next attempt.

There are no apparent issues when suspending to and resuming from "deep" state.

On a system with Mesa 25.1.3 shows OpenGL 4.3 with no Vulkan.

$ glxinfo | grep "Device\|OpenGL core profile version\|Dedicated video memory"
    Device: NVF1 (0x100a)
    Dedicated video memory: 3056 MB
OpenGL core profile version string: 4.3 (Core Profile) Mesa 25.1.3
$ vulkaninfo | grep deviceType
	deviceType        = PHYSICAL_DEVICE_TYPE_CPU
	deviceType        = PHYSICAL_DEVICE_TYPE_CPU

The coolers on the card are sped up and slowed down seemingly according to the work load.

When tested with a UHD monitor, the following resolutions showed up.

$ cat /sys/class/drm/card0-HDMI-A-1/status /sys/class/drm/card0-HDMI-A-1/modes
connected
2560x1440
1920x1080
1920x1080
1920x1080
1920x1080
1920x1080i
1920x1080i
1920x1080
1920x1080i
1680x1050
1600x900
1280x1024
1280x1024
1280x800
1152x864
1280x720
1280x720
1280x720
1280x720
1024x768
1024x768
832x624
800x600
800x600
720x576
720x576
720x480
720x480
720x480
720x480
640x480
640x480
640x480
640x480
720x400

The frequency depends on the resolution, the cable, and possibly on the monitor. Tested: 2560x1440@59.95 over HDMI.

The nouveau driver does not support automatic reclocking for this card. This is expected per the nouveau's power management matrix: https://nouveau.freedesktop.org/PowerManagement.html. The following modes are available.

$ sudo cat /sys/kernel/debug/dri/0/pstate
07: core 324 MHz memory 648 MHz
0a: core 324-692 MHz memory 1620 MHz
0d: core 549-1097 MHz memory 7000 MHz
0f: core 549-1097 MHz memory 7000 MHz AC DC
AC: core 887 MHz memory 6999 MHz

For example, to enable 0f mode on boot, add nouveau.config=NvClkMode=15 to kernel parameters.

$ glmark2 --fullscreen
=======================================================
    glmark2 2023.01
=======================================================
    OpenGL Information
    GL_VENDOR:      Mesa
    GL_RENDERER:    NVF1
    GL_VERSION:     4.3 (Compatibility Profile) Mesa 25.1.3
    Surface Config: buf=32 r=8 g=8 b=8 a=8 depth=24 stencil=0 samples=0
    Surface Size:   2560x1440 fullscreen
=======================================================
[build] use-vbo=false: FPS: 3528 FrameTime: 0.283 ms
[build] use-vbo=true: FPS: 4131 FrameTime: 0.242 ms
[texture] texture-filter=nearest: FPS: 3917 FrameTime: 0.255 ms
[texture] texture-filter=linear: FPS: 3912 FrameTime: 0.256 ms
[texture] texture-filter=mipmap: FPS: 3944 FrameTime: 0.254 ms
[shading] shading=gouraud: FPS: 3998 FrameTime: 0.250 ms
[shading] shading=blinn-phong-inf: FPS: 3960 FrameTime: 0.253 ms
[shading] shading=phong: FPS: 3915 FrameTime: 0.255 ms
[shading] shading=cel: FPS: 3873 FrameTime: 0.258 ms
[bump] bump-render=high-poly: FPS: 3726 FrameTime: 0.268 ms
[bump] bump-render=normals: FPS: 4071 FrameTime: 0.246 ms
[bump] bump-render=height: FPS: 3909 FrameTime: 0.256 ms
[effect2d] kernel=0,1,0;1,-4,1;0,1,0;: FPS: 2378 FrameTime: 0.421 ms
[effect2d] kernel=1,1,1,1,1;1,1,1,1,1;1,1,1,1,1;: FPS: 1467 FrameTime: 0.682 ms
[pulsar] light=false:quads=5:texture=false: FPS: 3109 FrameTime: 0.322 ms
[desktop] blur-radius=5:effect=blur:passes=1:separable=true:windows=4: FPS: 1124 FrameTime: 0.890 ms
[desktop] effect=shadow:windows=4: FPS: 1478 FrameTime: 0.677 ms
[buffer] columns=200:interleave=false:update-dispersion=0.9:update-fraction=0.5:update-method=map: FPS: 1240 FrameTime: 0.807 ms
[buffer] columns=200:interleave=false:update-dispersion=0.9:update-fraction=0.5:update-method=subdata: FPS: 1362 FrameTime: 0.735 ms
[buffer] columns=200:interleave=true:update-dispersion=0.9:update-fraction=0.5:update-method=map: FPS: 1406 FrameTime: 0.711 ms
[ideas] speed=duration: FPS: 626 FrameTime: 1.599 ms
[jellyfish] <default>: FPS: 2343 FrameTime: 0.427 ms
[terrain] <default>: FPS: 141 FrameTime: 7.108 ms
[shadow] <default>: FPS: 2801 FrameTime: 0.357 ms
[refract] <default>: FPS: 697 FrameTime: 1.435 ms
[conditionals] fragment-steps=0:vertex-steps=0: FPS: 3778 FrameTime: 0.265 ms
[conditionals] fragment-steps=5:vertex-steps=0: FPS: 3599 FrameTime: 0.278 ms
[conditionals] fragment-steps=0:vertex-steps=5: FPS: 3761 FrameTime: 0.266 ms
[function] fragment-complexity=low:fragment-steps=5: FPS: 3775 FrameTime: 0.265 ms
[function] fragment-complexity=medium:fragment-steps=5: FPS: 3680 FrameTime: 0.272 ms
[loop] fragment-loop=false:fragment-steps=5:vertex-steps=5: FPS: 3733 FrameTime: 0.268 ms
[loop] fragment-steps=5:fragment-uniform=false:vertex-steps=5: FPS: 3753 FrameTime: 0.266 ms
[loop] fragment-steps=5:fragment-uniform=true:vertex-steps=5: FPS: 3672 FrameTime: 0.272 ms
=======================================================
                                  glmark2 Score: 2932 
=======================================================