Topic: Problems Overclocking Antminer U2 to 2.6GH/s!! (Read 3936 times)

When you say USB do you mean USB input from the computer or supplied USB output power of the hub? I'm running 3 Anker 9+1 port hubs on an Asus G75 so I kind of just assumed for the price of these it would have been up to the task however I do know that laptops USB run at 3.3v for some reason while a desktop runs at a true 5v and USB 3.0 isn't working on my laptop since the Windows 8.1 upgrade so it's running at 3.3v but the hubs are still powered at a full 5v which I thought would compensate for the laptops 3.3v ports.

I just looked up some voltage mod info for these and this is exactly why the U1 can only be overclocked to 2.0GH/s because it's limited to 0.8v, which the U2 has a 10k resistor already installed from Bitmain in the R2 slot which puts it at 0.9v minimum.

I'm not sure if Bitmain upgraded the R1 resister? What is the standard running voltage of the Antminer U2? Anyone know if Bitmain upgraded the R1 resistor so I would know where to start from?

It's really a shame they didn't make this upgrade easier as it's a SMD resistor, it's going to suck to change, and to change 3 times until I figure out what maximum voltage and overclock frequency to keep a stable temperature with how many fans I have, and then do it 9 more times for the other ones lol.

You've reached the limit of the power that can be supplied by USB.

Can you increase a voltage. They need more juice in my opinion
Volt mod or something

I have 10 Antminer U2's that I was running at 1.6GH/s when I got them, after my Arctic Breeze fans came in, I overclocked them to 2.2GH/s and now recently I noticed you can just keep going, there's overclock support for up to 4GH/s if you can get it working with proper cooling.

Now when I found out about these new values for overclocking further then the "supported" 2.2GHz (x0A81), I decided I would start testing slowly one step up at at time until I notice the heat increase so I stepped them up to 2.4GH/s (x0B81) and ran those for about a week, didn't heat up at all, the fans are keeping the heat sinks cold to the touch from ambient room temperature.

The problem though, is earlier tonight I decided it's time for the next step and upped it to 2.6GH/s with x4C81 only to have crazy hardware errors (something around 13-15% on boot and they just kept climbing). After this happened, I would have to disconnect everything, plug each hub back in with nothing in them, and plug each Antminer U2 back in the hubs one at a time while the hub was powered on just to get all 10 working again otherwise only 4 would come up if I tried to open my .bat file again after changing the overclock value back down.

So does anyone know why my Antminer U2's run flawless at 2.4GH/s (x0B18) but as soon as they're set to 2.6GH/s (x4C81) they go crazy and then only 4 work until I unhook everything and hook them up one at a time? They're handing 2.4GH/s just fine, still cold even so I don't see why 2.6GH/s would be so glitchy when they're barely even making heat with how I have them cooled.

EDIT:
I forgot to add, I tried 2.8GH/s just to see if maybe it was a 2.6GH/s issue, perhaps skip it and go on to the next but that wasn't the case, as soon as I opened BFG Miner when set to 2.8GH/s (x4D81) they went from all 0 to 100% hardware errors instantly.

I just don't understand why it's such a drastic jump in issues. I've been back on 2.4GH/s for about a half hour now and I still have 0 hardware errors but 0.2GH/s more and it jumps to a 13-15% starting rate for hardware errors and keeps going up, then another 0.2GH/s more and they start off at 100% hardware error.