Both should be connected to the GPU. My log, nothing connected to the iGPU.
20:29:45.462: CPU Name: 12th Gen Intel(R) Core(TM) i9-12900K
20:29:45.462: CPU Speed: 3187MHz
20:29:45.462: Physical Cores: 16, Logical Cores: 24
20:29:45.463: Physical Memory: 32476MB Total, 25368MB Free
20:29:45.463: Windows Version: 10.0 Build 19044 (release: 21H2; revision: 2604; 64-bit)
20:29:45.463: Running as administrator: false
20:29:45.463: Windows 10/11 Gaming Features:
20:29:45.463: Game Bar: Off
20:29:45.463: Game DVR: Off
20:29:45.463: Game DVR Background Recording: Off
20:29:45.463: Game Mode: Off
20:29:45.463: Sec. Software Status:
20:29:45.464: Microsoft Defender Antivirus: enabled (AV)
20:29:45.465: Windows Firewall: enabled (FW)
20:29:45.465: Current Date/Time: 2023-03-12, 20:29:45
20:29:45.465: Browser Hardware Acceleration: false
20:29:45.465: Hide OBS windows from screen capture: false
20:29:45.465: Qt Version: 6.3.1 (runtime), 6.3.1 (compiled)
20:29:45.465: Portable mode: false
20:29:45.488: OBS 29.0.2 (64-bit, windows)
20:29:45.488: ---------------------------------
20:29:45.488: ---------------------------------
20:29:45.488: audio settings reset:
20:29:45.488: samples per sec: 48000
20:29:45.488: speakers: 2
20:29:45.488: max buffering: 960 milliseconds
20:29:45.488: buffering type: dynamically increasing
20:29:45.489: ---------------------------------
20:29:45.489: Initializing D3D11...
20:29:45.489: Available Video Adapters:
20:29:45.490: Adapter 0: NVIDIA GeForce RTX 3090
20:29:45.490: Dedicated VRAM: 4055891968
20:29:45.490: Shared VRAM: 4142000128
20:29:45.490: PCI ID: 10de:2204
20:29:45.490: Driver Version: 31.0.15.2230
20:29:45.490: output 0:
20:29:45.490: name=ROG PG259QN
20:29:45.490: pos={0, 0}
20:29:45.490: size={1920, 1080}
20:29:45.490: attached=true
20:29:45.490: refresh=60
20:29:45.490: bits_per_color=8
20:29:45.490: space=RGB_FULL_G22_NONE_P709
20:29:45.490: sdr_white_nits=80
20:29:45.490: nit_range=[min=0.098400, max=400.000000, max_full_frame=351.276398]
20:29:45.490: output 1:
20:29:45.490: name=AVM 50v
20:29:45.490: pos={1920, 0}
20:29:45.490: size={1920, 1080}
20:29:45.490: attached=true
20:29:45.490: refresh=60
20:29:45.490: bits_per_color=8
20:29:45.490: space=RGB_FULL_G22_NONE_P709
20:29:45.490: sdr_white_nits=80
20:29:45.490: nit_range=[min=0.500000, max=270.000000, max_full_frame=270.000000]
20:29:45.490: output 2:
20:29:45.490: name=ASUS VG236
20:29:45.490: pos={-1920, 0}
20:29:45.490: size={1920, 1080}
20:29:45.490: attached=true
20:29:45.490: refresh=60
20:29:45.490: bits_per_color=8
20:29:45.490: space=RGB_FULL_G22_NONE_P709
20:29:45.490: sdr_white_nits=80
20:29:45.490: nit_range=[min=0.500000, max=270.000000, max_full_frame=270.000000]
20:29:45.490: Adapter 1: Intel(R) UHD Graphics 770
20:29:45.490: Dedicated VRAM: 134217728
20:29:45.490: Shared VRAM: 4142000128
20:29:45.490: PCI ID: 8086:4680
20:29:45.491: Driver Version: 31.0.101.4146
20:29:45.492: Loading up D3D11 on adapter NVIDIA GeForce RTX 3090 (0)
20:29:45.548: D3D11 loaded successfully, feature level used: b000
20:29:45.548: DXGI increase maximum frame latency success
20:29:45.548: D3D11 GPU priority setup failed (not admin?)
20:29:46.308: ---------------------------------
20:29:46.308: video settings reset:
20:29:46.308: base resolution: 1920x1080
20:29:46.308: output resolution: 1920x1080
20:29:46.308: downscale filter: Bicubic
20:29:46.308: fps: 60/1
20:29:46.308: format: NV12
20:29:46.308: YUV mode: Rec. 709/Partial
20:29:46.308: NV12 texture support enabled
20:29:46.308: P010 texture support not available
20:29:46.309: Audio monitoring device:
20:29:46.309: name: Default
20:29:46.309: id: default