newest is better, but any version works for me, please
I have an SP20

With the difficulty rising nearly exponentially is anyone really making money with this miner?  Doing the calculations it seems literally impossible to be profitable.

One of my returned R4's drop a board this afternoon, a quick restarted got it going again. It had been mining for just a touch over 7 days since it was returned. This makes me a little nervous.

Edit: Using the unreliable Kill-o-Watt meter im seeing an efficiency of about .15 or so. Going to amp clamp it later and see if I can get slightly more accurate readings.

Look at my R4... Does the status look ok regarding temperature or is one of the boards not reporting temp? Am I reading it correctly? Where it says '-' should there be temperature? it's hashing at full 8.7 TH/s speed.

Well, this seems to be rather common now.  My one R4 B2 that's been running for 4 weeks had one board stop working yesterday.  After reading here that it's been happening to others and that some have gotten it working again by updating the firmware, I tried that also.  Firmware update seemed to go fine, but only 1 board working still and after the firmware update the other board seems to be working but it's showing a large number of total HW errors even though the working board errors are almost none.  Now what?

What are you doing about a fix? Sending back to Hong Kong? Denver? Entire unit or only board? Bitmainwarranty is not answering the phone or replying to emails

One of my R4's that stopped hashing on one board has stopped hashing completely after trying to restore the original firmware. The hardware version listed under system overview says "   Socket connect failed: Connection refused".

I have tried powering off several times, reboots, updating firmware, etc. No more hashing. There has to be an easy fix to this without sending to Hong Kong or letting sit in Denver for weeks on end. Any thoughts?

EDIT:  unplugged the original board that did not hash and fired back up, the one remaining board is hashing again at 4th/s!

Agree. Unless electricity is free ROI difficult

I have a Batch 2 R4 that stopped hashing on one board, Miner status page still shows circles and not x, but very high HW on the board not hashing. Any ideas?

Please update the firmware: https://shop.bitmain.com/support.htm?pid=007201612090211421457I07aFFE0609
For details on how to upgrade the firmware please see the User manual: https://shop.bitmain.com/support.htm?pid=007201608300453591291gt4d83P0660

If that does not solve the issue then please first test the controller. You can switch the controller cables between hash boards. If the issue follows the cable then the controller is faulty and you can ship the controller to us for repair.

If that does not solve the issue then please test the hash boards one by one.

To test each hash board separately: keep the PSU connectors and controller cable on one of the hash boards connected and disconnect the cables from the other two hash boards. With the miner running you can see the status of the connected hash board.

Here is more detail: http://support.bitmain.com/hc/en-us/articles/226142788-Testing-hash-board-one-by-one

On the miner status screen defective chips are displayed as "xxx", "---" or " ASIC≠45(s7) or 63(s9)"

Once you know which part is defective please create a Repair ticket and ship the part back to us according to these instructions: https://cnshop.bitmain.com/workOrderGuide.htm

Sorry I am too lazy to check my R4B2. Mine just stopped hashing this morning where GH/s(RT) read 0 but everything else looked correct. Every share was rejected. Tried switching pools via MRR, no improvements. Tried flashing 1202 fw, it errored out and i freaked out too. but it rebooted itself and now everything's back up right.

I don't know what to say about these rigs. I hope they are of decent quality.

The r4 seriously in need of overclock

So some questions to ask:
1) what was the psu you used?
2) how was the room it was in?  by that was it really hot or really cold?  above 90 f or below 35 f ?

They want whole unit? seems a bit much.. won't let you just send the one board?

Yes, you do need to send the whole machine. The boards work together and they cannot repair one board without the other.

 There are still S7-LN and S5 units available - from NewEgg.

You don't need to add VAT if its within the EU as you are not a business buying them in and selling them to the public.

How about a picture of your S9 with a piece of paper with your forum name and date written on showing you actually have what you are selling. Maybe you'll get some interest then