# Lotus Miner: Custom GPUs
This guide explains how to benchmark and test GPUs model that is not explicitally supported by the Lotus Miner.
The list of known-to-work supported GPUs is in the hardware-requirements.
# Enabling a custom GPU
If you want to test a GPU that is not explicitly supported, set the following environment variable:
export BELLMAN_CUSTOM_GPU="<NAME>:<NUMBER_OF_CORES>"
Here is an example of trying a GeForce GTX 1660 Ti with 1536 cores:
export BELLMAN_CUSTOM_GPU="GeForce GTX 1660 Ti:1536"
TIP
To get the number of cores for your GPU, you will need to check your card's specifications.
# Testing whether the GPU is used
First, to watch GPU utilization run nvtop in one terminal, then in a separate terminal, run the benchmarking tool to simulate sealing of a sector of small size:
./lotus-bench sealing --sector-size=2KiB
This process uses a fair amount of GPU, and generally takes ~4 minutes to complete. If you do not see any activity in nvtop from lotus during the entire process, it is likely something is misconfigured with your GPU.