Technically, 5MH at 3W/MH is possible using the upcoming
But you'll only need 2, maybe 3 chips.
2A * 5v = 10w.
3w/MH * 5-6.9MH = 15-21w
They didn't even bother to do some math.
And don't expect to draw 15w from your standard USB port...
Afaik, the "minion2" chips they are supposed to use doesn't exist.
Their SHA2(5)6 usb miner is even better:
Hashrate: ~100GH/s out of the box, up to 120GH/s overclocked,
Power usage: ~0.75W per GH,
Dimentions: 28x60mm without usb plug,
Power requirement: 2-2.5A
0.75w/GH * 100GH = 75w
5v x2A = 10w
It seems that besides hashing, those USB stick are even generating the extra power they need to run
pictures are simply some old Block erupter USB with a photoshopped logo on it.
Don't waste your time with them.
For in stock scrypt miners, you should search some second hand Gridseed blades/G-black.
I'd avoid Zeus/Gaw miners since efficiency is worst than Gridseed, and they don't like undervolt to acheive better efficiency.
If you can afford and find them, Alcheminer 256/MAT excalibur could be a good choice, but they don't work weel on all pools.
KNC TITAN is overpriced, and it's KNC, but the most efficient option available right now.