I'm curious, how do you tell if you are getting a counterfeit card? I just had to send one back because it simply didn't work right, it looked legit but who knows.
I don't have a sure way to identify counterfeits, but these are a few things I've noticed as "patterns":
1) the "LSI" print is missing. usually "LSI" is printed on the PCB near the PCI-E connector
2) the heatsink looks larger and attached with plastic (black colored) pins. What i believe are genuine LSI cards have brass colored spring loaded pins.
when I see the above, I send a message to the seller asking about the card's origins; and i usually get no reply at all. where as, the ones that I think look genuine, the sellers usually respond.
none of this is definite, but for me it does raise suspicion and makes me speculate the item is counterfeit. in some of these cases, i've spoken to LSI/Broadcom about it and they agreed with my speculation. interesting thing is, they don't appear interested in dealing with them as when I asked to escalate to legal, their response was basically they don't worry about it.