I found swap chain created with flip model (DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL or DXGI_SWAP_EFFECT_FLIP_DISCARD) was locked to VSync (1/60 sec), calling IDXGISwapChain1::Present1 method with SyncInterval set to 0 as follows doesn't work.
swap_chain->Present1(0, 0, ¶m);
Does anyone know how to disable VSync for DXGI flip model?