System Check

Before you post "why is this so slow" or "why won't this node install" on r/comfyui, run this node first. System Check doesn't touch your image generation at all - it dumps everything about the machine ComfyUI is running on into a text report: OS, Python version, GPU and VRAM, CUDA, and whether the speed libraries (Triton, xFormers, Flash Attention) are actually installed and working. It's the ComfyUI equivalent of "About This PC," except it also tells you whether your attention backend is doing its job.

Why you'd bother

Most of what makes a workflow fail or crawl isn't a missing node - Manager handles that part fine. It's an environment mismatch: wrong CUDA build, xFormers compiled against a different torch version, no Flash Attention so everything falls back to slower attention math. Manager can tell you a node is installed; it can't tell you your Python/CUDA/library versions don't line up with what the workflow author had. That's the gap this node fills, and it's a real one - the ComfyUI ecosystem doesn't have a great built-in way to answer "is my setup actually fine?" without opening a terminal and running four separate commands. This node runs those checks for you and hands back one readable block of text, or a structured object if you want to do something with it downstream.

The inputs and outputs that matter

Just two inputs, both required:

• check_type - BASIC or DETAILED, defaults to DETAILED. Basic gets you OS, Python version, GPU/VRAM, CUDA, and pass/fail status on Triton, xFormers, Flash Attention, and SDPA. Detailed adds PyTorch build internals (debug mode, OpenMP/MKL, MAGMA), deeper CUDA device properties, a much longer library scan (numpy, opencv, transformers, diffusers, einops, safetensors, plus face/vision libraries like insightface, dlib, mediapipe), and system resource stats like RAM and CPU. Start with BASIC for a quick sanity check; switch to DETAILED when you're actually debugging something and need the extra ammunition for a bug report.
• save_report - a boolean, off by default. Flip it to write the report out to disk as well as returning it as an output - handy if you want to paste the whole thing into a GitHub issue or a subreddit post later instead of re-running the node. The README doesn't spell out the exact file location, so check the ComfyUI console/output folder after a run if you're hunting for it.

Two outputs. report is a plain STRING - wire it into any node that takes text, or the simplest option, a Show Text / Print node, to just read it. data is a SYSTEM_INFO type, which is this pack's own custom socket type rather than a generic value - its only real use is feeding the companion System Visualization node from the same pack, which takes that structured data and turns it into a second-stage STRING output.

Installing it

Search ComfyUI Manager for "System Check" or "comfycheck." If it's not showing up there, do it by hand:

cd ComfyUI/custom_nodes
git clone https://github.com/Kurdknight/Kurdknight_comfycheck

Restart ComfyUI and look for System Check under the utils category. That's genuinely it - the whole pack only needs torch and psutil, both of which any working ComfyUI install already has. No model downloads, no pip hell, nothing to configure. It's one of the lighter node packs you'll ever install, which fits its job: it's a diagnostic tool, not a generation tool.

Common issues

The one real snag worth knowing about isn't specific to this node - it's specific to how you probably installed it. If you load someone else's workflow and let Manager mass-install a batch of missing custom nodes in one go, a dependency conflict from one of those packs can take down node packs that were working fine before, this one included; people have reported seeing Kurdknight_comfycheck show up as (Import Failed) in the console purely as collateral damage from an unrelated pack's pip install. If System Check stops loading, check the ComfyUI startup console for the actual import error rather than assuming this pack broke - nine times out of ten the traceback points at something else entirely.

Beyond that, there's not much to troubleshoot. If a library shows as "not found" in the report, that's not a bug - it means you genuinely don't have it installed, and this node doesn't install anything for you; it only reports. Missing Triton or Flash Attention just means you're running on ComfyUI's default (slower but universal) attention path instead of the accelerated one - worth knowing before you go chasing a performance problem elsewhere.