NCC version and Pytorch NCCL version mismatch

I have NCCL 2.5 installed on the system, but torch.cuda.nccl.version() shows 2.4.8.
On a single machine with 2 gpus, it works fine.

Hey @nash, NCCL is packaged in PyTorch as a submodule. The current version if 2.4.8. If you would like to use your own version, you can set USE_SYSTEM_NCCL=1.

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