# RaySGD fails to find GPUs

**URL:** <https://discuss.ray.io/t/raysgd-fails-to-find-gpus/3931>\
**Category:** Ray Train\
**Created:** [October 26, 2021, 12:46pm UTC](https://discuss.ray.io/t/raysgd-fails-to-find-gpus/3931 "2021-10-26T12:46:17Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Lacruche](https://avatars.discourse-cdn.com/v4/letter/l/ecccb3/32.png) [@Lacruche](https://discuss.ray.io/u/Lacruche)\
**Post date:** [October 26, 2021, 12:46pm UTC](https://discuss.ray.io/t/raysgd-fails-to-find-gpus/3931/1 "2021-10-26T12:46:17Z")

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Hi,  
I’m using RaySGD on an EC2 instance that has 4 T4 GPUs.  
single-GPU training runs fine on one GPU in PyTorch. When I try using RaySGD to use the 4 GPUs, I get:

`/home/ec2-user/anaconda3/envs/pytorch_latest_p37/lib/python3.7/site-packages/torch/cuda/amp/grad_scaler.py:116: UserWarning: torch.cuda.amp.GradScaler is enabled, but CUDA is not available. Disabling.`

Why Ray doesn’t see my 4 GPUs?

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<div class="post-metadata">

**Author:** ![amogkam](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ray.io/amogkam/32/17_2.png) [@amogkam](https://discuss.ray.io/u/amogkam)\
**Post date:** [December 6, 2021, 6:25pm UTC](https://discuss.ray.io/t/raysgd-fails-to-find-gpus/3931/2 "2021-12-06T18:25:32Z")

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Hey @Lacruche do you mind sharing a longer stack trace and a code snippet? Thanks!