GPU: AMD Radeon RX 7700 XT / 7800 XT (Navi 32, gfx1101)
- VRAM Total: 12 GB (12,868,124,672 bytes)
- TDP: 200W (configurable)
- Memory Clock States: 96 MHz (idle) → 1124 MHz (max)
Display Configuration (4 Monitors):
| Display | Connection | Resolution | Refresh Rate | Orientation |
|---|---|---|---|---|
| DP-1 | DisplayPort | 1920×1080 | 60 Hz | Landscape |
| DP-2 | DisplayPort | 1920×1080 | 60 Hz | Landscape |
| HDMI-A-1 | HDMI | 1024×600 | 60 Hz | Portrait (rotated) |
| HDMI-A-2 | HDMI | 1920×1080 | 60 Hz | Landscape |
Total Desktop Resolution: 6360×1080 effective (with portrait display adding 600×1024)
The GPU allocates framebuffer memory for each display. For double-buffering (standard) and 10-bit color depth:
Formula: Width × Height × Bytes per Pixel × Buffer Count
For 10-bit color (as reported), using 4 bytes per pixel (32-bit aligned):
| Display | Pixels | Single Buffer | Double Buffer |
|---|---|---|---|
| DP-1 (1920×1080) | 2,073,600 | 8.29 MB | 16.59 MB |
| DP-2 (1920×1080) | 2,073,600 | 8.29 MB | 16.59 MB |
| HDMI-A-1 (1024×600) | 614,400 | 2.46 MB | 4.92 MB |
| HDMI-A-2 (1920×1080) | 2,073,600 | 8.29 MB | 16.59 MB |
| Configuration | Total Pixels | Framebuffer (Double) | % of 12GB VRAM |
|---|---|---|---|
| 1 Display (1080p) | 2,073,600 | 16.59 MB | 0.14% |
| 2 Displays (1080p) | 4,147,200 | 33.18 MB | 0.27% |
| 3 Displays (2×1080p + 600p) | 4,761,600 | 38.09 MB | 0.31% |
| 4 Displays (Current) | 6,835,200 | 54.68 MB | 0.44% |
Key metric: How much data must the GPU push to displays per second?
Formula: Pixels × Bytes per Pixel × Refresh Rate
| Configuration | Bandwidth Requirement |
|---|---|
| 1 Display (1920×1080@60Hz) | 498 MB/s |
| 2 Displays (1080p) | 996 MB/s |
| 3 Displays (Current mix) | 1,144 MB/s |
| 4 Displays (Current) | 1,642 MB/s |
GPU Memory Bandwidth Available:
- Idle (96 MHz): ~12.3 GB/s (192-bit bus)
- Max (1124 MHz): ~144 GB/s
Display requirements represent ~1.1% of idle bandwidth and ~0.11% of max bandwidth.
- GPU Power: 14W (idle desktop)
- GPU Load: 1%
- Memory Clock: 96 MHz (lowest state)
- VRAM Usage: 1.72 GB (13% - includes compositor, apps)
Based on typical RDNA 3 display engine characteristics:
| Component | Power per Display | Notes |
|---|---|---|
| Display Controller (CRTC) | ~0.5-1W | Per active output |
| PHY/Transmitter (DP/HDMI) | ~0.3-0.5W | Signal transmission |
| Compositor overhead | ~0.2-0.5W | KWin/Wayland |
Estimated Display Engine Power:
| Configuration | Display Engine Power | Notes |
|---|---|---|
| 1 Display | ~1-2W | Baseline |
| 2 Displays | ~2-4W | +1-2W |
| 3 Displays | ~3-5W | +1-2W |
| 4 Displays | ~4-6W | +1-2W |
| Configuration | Est. Total Idle Power | vs. Single Display |
|---|---|---|
| 1 Display | ~10-11W | Baseline |
| 2 Displays | ~11-13W | +1-2W (+10-15%) |
| 3 Displays | ~12-14W | +2-3W (+20-25%) |
| 4 Displays | ~13-15W | +3-4W (+30-40%) |
Your observed 14W aligns with 4-display idle expectations.
Beyond framebuffers, each display adds:
- Cursor planes: ~4 KB per display
- Overlay planes: ~varies
- Compositor surfaces: ~8-16 MB per display (KWin)
Estimated Total VRAM per Display:
| Configuration | Est. VRAM (Desktop Idle) |
|---|---|
| 1 Display | ~400-500 MB |
| 2 Displays | ~600-800 MB |
| 3 Displays | ~800-1000 MB |
| 4 Displays | ~1000-1200 MB |
Your observed 1.72 GB includes running applications beyond desktop composition.
| Metric | Per Additional 1080p Display |
|---|---|
| Framebuffer VRAM | +16.6 MB |
| Compositor VRAM | +8-16 MB |
| Display Bandwidth | +498 MB/s |
| Power (idle) | +1-2W |
| Power (% increase) | +8-15% |
- VRAM impact is minimal - Even 4 displays use <1% of VRAM for framebuffers
- Bandwidth is negligible - Display output uses ~1% of idle memory bandwidth
- Power is the main cost - Each display adds ~1-2W at idle (~10-15% per display)
- GPU compute unaffected - Display engine is separate from shader cores
- Running 4 displays on your RX 7700 XT has no meaningful impact on gaming or compute performance
- The ~4W additional idle power for 4 vs 1 display costs roughly $3-5/year (at average electricity rates)
- Memory bandwidth for displays is handled by dedicated display engine, not competing with GPU compute
Date: 2025-11-25
GPU: AMD Radeon RX 7700 XT / 7800 XT (Navi 32)
VRAM Total: 12,868,124,672 bytes (12 GB)
VRAM Used: 1,721,495,552 bytes (1.72 GB, 13%)
GPU Temp: 42°C
GPU Power: 14W (idle)
GPU Load: 1%
Memory Clock: 96 MHz (idle state)
Core Clock: 43 MHz (idle state)
This gist was generated by Claude Code. The calculations are based on industry-standard formulas and typical RDNA 3 architecture characteristics. Actual values may vary based on driver versions, compositor settings, and specific GPU SKU. Users should validate with their own measurements using tools like rocm-smi, radeontop, or power meters.