some questions about loading checkpoints
What I have tried:

defined a Lighting Module class: model=LitModel(hparams),
then I trained the model and got a checkpoint;
since I want to visualize the features of the trainset, I write a another file and loading the checkpoint, model = LitModel(hparams).load_from_checkpoint('lightning_logs/version_90/checkpoints/epoch=119.ckpt')

My questions are:

I have to add a line model.eval() before model(samples), otherwise, the accuracy is very low! however, to my best knowledge, in common pytorch code, the accuracy of the trainset has no matter with model.eval(), so why model.eval() take effects?
I tried to put my model onto gpumodel = LitModel(hparams).load_from_checkpoint('lightning_logs/version_90/checkpoints/epoch=119.ckpt').cuda(), the model takes up about 460M/11G, however, when running into model(samples.cuda()), my gpu memory is out of use! so, can anyone show me the correct way to visualize features using the checkpoint of Light Module?