Shares mostly rejected mining with an FPGA

Question

I am using an FPGA to mine bitcoins in a pool, as you can see below I am not really very successful:

[1 accepted, 48 failed, 148.90 +/- 21.27 Mhash/s]

It is running at 150 MhZ but I only have 1 accepted share out of 49. I guess this quota does not look to healhty. Anyone an idea what could be wrong?

Answer 1

Give me the make of the FPGA and the name of FPGA binary you are using.

It could well be that you are over-clocking the FPGA too far, due to the way that many of these cores are designed, there is a race condition, where the "success" flag, gets out of sync with the "nonce".

Basically the FPGA flags the "hit", but by the time it gets to copying the "nonce", it has changed...... and so fails.