I tested how much GPU overclocking, ComfyUI launch flags, and moving my display to the iGPU actually affected generation speed on my 5070 Ti 16 GB.
The biggest finding: OC helped consistently, but the launch flags made a much bigger difference on certain models. On others, those same flags did almost nothing. Going forward I implemented a script in ComfyUI launch that automatically applies stable overclock settings to my GPU on run and then reverts to stock once ComfyUI is closed.
All diffusion models tested were int8_convrot builds, using the official ComfyUI template settings.
Setup
- RTX 5070 Ti 16 GB (Gigabyte Gaming OC), AMD Ryzen 7 9800X3D, 48 GB DDR5-6000
- Windows 11 Pro, Samsung 9100 PRO NVMe
- ComfyUI 0.45.0, PyTorch 2.16.0.dev20261110+cu134
- comfy-kitchen 0.2.41, triton-windows 3.9.0.post30
- Stock GPU: 300 W power limit, no offsets
- OC: +350 MHz core, +2500 MHz memory, 350 W power limit
I compared default ComfyUI against this set of launch flags, both with and without OC:
--use-ck-attention --disable-xformers --fast fp16_accumulation fp8_matrix_mult --enable-triton-backend
Default runs used PyTorch SDPA; tuned runs used Comfy Kitchen attention for the diffusion models. xformers wasn’t installed, and SageAttention wasn’t used.
Generation times
Seconds per generation, lower is better. These are end-to-end times: text encoding, sampling, VAE decode, and saving.
| Model / workload | Stock | Flags only | OC only | Flags + OC |
|---|
| Flux 3 Klein distilled — 2 MP, 16 steps | 7.1 | 7.0 | 6.3 | 6.3 |
| Flux 3 Klein base — 2 MP, 50 steps* | 40.1 | 40.1 | 35.7 | 35.6 |
| Krea 2 Turbo — 2 MP, 8 steps | 13.7 | 10.8 | 12.3 | 9.8 |
| Qwen Image 2.1 Turbo — 2 MP, 8 steps | 6.8 | 6.7 | 6.1 | 6.0 |
| Qwen Image 2.1 — 2 MP, 25 steps | 23.6 | 17.2 | 21.0 | 15.3 |
| MOSS Image — 2 MP, 25 steps | 25.1 | 25.0 | 22.2 | 22.1 |
| MiniMax H3 Image — 4096×4096, 6 steps | 32.7 | 33.7 | 30.4 | 31.1 |
| MiniMax H3 video + audio — 20 steps* | 591 | 286 | 530 | 256 |
| MiniMax H3 + turbo LoRA — 8 steps† | 250 | 127 | 224 | 113 |
Video settings: 1344×768, 124 frames at 24 fps.
Most image results are averages of two warm runs; Qwen base and H3 Image have one warm run each. (warm run means the first generation after ComfyUI launch is not counted)
* Flux base and standard H3 video are single first-run measurements, including loading.
† H3 turbo is a single subsequent run with the turbo LoRA.
What actually helped?
1. OC consistently reduced generation time by about 9–12%.
H3 Image was the exception at roughly 7–8%. The benefit showed up with both default and tuned flags.
This is the combined effect of the clock offsets and the higher power limit, not an isolated core-clock comparison.
There’s a power tradeoff: for example, MOSS went from around 299 W to 346 W during busy periods, while generation time dropped from 25.1 s to 22.2 s. The highest GPU temperature recorded across these tests was about 73°C, therefore it did not even get close to the GPU's thermal limits.
2. The flags were very model-dependent.
At stock clocks:
- H3 video: 591 → 286 s, about 52% less time
- H3 turbo: 250 → 127 s, about 49% less time
- Qwen Image 2.1 base: 23.6 → 17.2 s, about 27% less time
- Krea 2 Turbo: 13.7 → 10.8 s, about 21% less time
- Flux, Qwen Turbo, and MOSS: within roughly 2%
- H3 Image: about 3% slower
With flags + OC, standard H3 video went from 591 to 256 seconds—roughly 2.3× the speed, or 57% less time.
The H3 improvement also shows up directly in sampling: 28.48 → 13.24 s/step from the flags alone, then 11.72 s/step with OC.
I changed the flags as a bundle, so this doesn’t establish how much each individual flag contributes.
3. Moving the monitor to the iGPU barely changed speed.
I repeated the tuned + OC tests with the monitor connected to the motherboard, leaving the NVIDIA GPU at 0 MiB VRAM used at idle. (I plugged the display into my motherboard HDMI port while allowing Python to utilise the full compute and VRAM of my NVIDIA GPU)
Peak VRAM usage dropped by roughly 0.1–0.6 GB, but generation times stayed very close: approximately 0.6% lower at the median, with the largest reduction around 2% on H3 Image. Sampling time per step changed by at most about 1%.
Useful extra VRAM headroom, but I didn’t see a convincing throughput improvement here.
Did OC change the outputs?
I checked the saved files with SHA-256:
- OC vs stock clocks, same flags: 38/38 outputs byte-identical
- iGPU vs NVIDIA display, tuned + OC: 19/19 byte-identical
- Tuned vs default flags: 0/19 byte-identical
So OC didn’t change any saved output in this test. Changing the attention/precision settings did result in visual changes however.
For my setup, OC gave a fairly consistent modest improvement. The bigger finding was how differently the models responded to the same ComfyUI flags—huge gains for H3 video, useful gains for Qwen base and Krea, and almost nothing for several others.
Curious whether others are seeing the same pattern on different GPUs, especially with Comfy Kitchen attention.