resource usage over 100%, but I can still run the design

Hello,

I am using nallatech pcie-385n a7 board and I tried the 1D FFT example from Altera ( https://www.altera.com/support/support-resources/design-examples/design-software/opencl/fft-1d.html)

When I set the FFT size to 8192, which is two times larger than the default size, I am still able to compile the design and run the design on the board I have. However , the estimate DSP blocks usage is 138% . I have two questions:

1. Why I am still able to run the design when the resource usage is over 100% ?

2. If the resource usage is just an estimated value, how do i know the exact resource usage ?

Thanks !