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Topic
Board Group buys
Re: [CLOSED] Bitmine CoinCraft A1 28nm chip distribution / DIY support
by
Gator-hex
on 19/03/2014, 01:22:41 UTC
Did Bitmine change chips specs?

Wasn't turbo 40GH? Now it is 33GH... But still same price... But I do agree I don't see way to get them to 40GH with normal cooling...

Well that's sad to see… I've still been hopeful that I could get 40 to work someday… It actually does kinda work, I just notice that when I over clock the chip I start dropping nonces (when running a known nonce test case)…

EDIT2: And from what I see you can't get 33GH out at 0.85V more like 0.985 to 1 V. Also 1W in Turbo mode is fantasy... More like 1,3 to 1,5W... Hard to say how much is the loss on chip power supply...

I haven't played with increasing the core voltage beyond 0.85V - still on the list. 1V really is necessary that's going to be a decent chunk of power indeed!

Has anyone been able to get 33GH/s or higher to run?

The current pricing really does need to be adjusted. Several competitors are all coming online very soon at well under $2/GH. I'd really prefer to stick with coin craft as I have a working design and am very happy with the support I've seen (zefir plus free samples). But the current pricing level is going to make it very hard to be profitable for long...

My experience with the Technobit Pre-production A1 chips is that they don't fire up until 850mV (Turbo) and then you'll be lucky to see 25GH (Normal).
They're in a top-30%/70%-bottom package so you'll need a heatsink on both sides and the power/temps rise quickly so you'll need a lot of cooling to get anywhere near 33GH. You need to raise the voltage as you raise the clock or you'll get hardware errors but 33GH is doable at 1040MHz(4x260)*/1000mV. Marto even managed to push it to 35GH at 1100MHz(4x275)*/1050mV
* The Bitmine clock is 4x the Technobit clock.