CUDA GPU solver running very slow.

Hello,

I'm using Nvidia GeForce GTX 650 with 384 cuda cores. Why solving process is running MUCH slower on my GPU card? My CPU is intel i3.

Case not large enough

Assuming your i3 CPU solver runs are using 2 cores then most likely your case isn't big enough - you need to run relatively large cases to see any speedup using the GPU. For more background see "CFD Performance Comparison Between GPU and CPU".