Today Claymore introduced a new version 6.1 Beta of dual miner with support for NVIDIA

Latest version v6.1 Beta:

FEATURES:

Supports new "dual mining" mode: mining both Ethereum and Decred or Siacoin at the same time, with no impact on Ethereum mining speed. Ethereum-only mining mode is supported as well.
Effective Ethereum mining speed is higher by 3-5% because of a completely different miner code - much less invalid and outdated shares, higher GPU load, optimized OpenCL code.
Supports both AMD and nVidia cards, even mixed.
No DAG files.
Supports all Stratum versions for Ethereum: can be used directly without any proxies with all pools that support eth-proxy, qtminer or miner-proxy.
Supports Ethereum and Siacoin solo mining.
Supports both HTTP and Stratum for Decred.
Supports both HTTP and Stratum for Siacoin. Note: not all Stratum versions are supported currently for Siacoin.
Supports failover.
Displays detailed mining information and hashrate for every card.
Supports remote monitoring and management.
Supports GPU selection, built-in GPU overclocking features and temperature management.
Supports Ethereum forks (Expanse, etc).
Windows and Linux versions.
This version is POOL/SOLO for Ethereum, POOL for Decred, POOL/SOLO for Siacoin.