Not marked it is luck of the draw. And they are hard to test. Once on board you will have hard time removing them. It is possible to make a test socket with springs but it would be expansive and hard...
I'm okay with that, luck of the draw it is then.
Its a shame the chips are of such an inferior quality but that is par for the course.
They do sell FPGA sockets, binning the chips would be good for everyone
I don't see why binning them would be good. Every chip has his own frequency and even if only one engine is working that is one engine more then without chip... And even samples are not that catastrophic...
From BFL Website:
Considerations:
Chip grades: Chips come in four grades of performance. Chips are sold in mixed grade lots. A grade has 16 engines, B grade has 15 engines, C grade has 14 engines and D grade has no less than 12 engines. All chips run at a minimum of 250 mhz. Higher grade chips will run up to 294mhz. The percentage distribution in each lot is 60% Grade A, 20% Grade B, 15% Grade C and 5% Grade D.
https://products.butterflylabs.com/65nm-asic-bitcoin-mining-chip.html
So we will see. I would guess you will need some BTC but not much but more importantly 8 chips. I guess you will get form 64 to 70GH out... But you need to know that this might not work so good because form reported that power regulation doesn't work that good...