Bitcoin Forum

I'm very very new to bitcoin (I just set up my bitcoin wallet yesterday).  I've been skimming material about bitcoin for about 6 months, but wanting to get a little deeper and potentially make a small profit.  I was almost certain I wanted to get an R4 or S9, but after reading a bit here it seems that they are not that reliable.  I then started looking at the a741 which seems to be much more reliable but significantly less efficient. 

If were starting today from scratch but knowing what you know, what would you go with?  In case it would come up or if somebody wants to let me know my calculations are off, my power cost .07952/kWh.  For the T9, I calculated a break-even time of 214 days assuming $1300 for hardware costs, current difficulty of 521974519554, bitcoin to dollar price of $1529.  For the a741, I calculated 321 assuming a hardware cost of $1000. 

Am I being overly optimistic assuming I can run one 24/7 for a year or until break-even.  What else am I missing?  I'm fine with it taking a year to break-even, but longer than that and I start to question whether I want to do mining at all.  Also, another thing I'm curious about is how people with dozens or even a couple got started.  Did you buy one and expand slowly from there or just make a decision when you got started and go all in?  Thanks in advance for all the help. 

BITMAIN have a six month warranty on their miners, but I'm pretty sure people have received heavily used miners back and other problems. 

The risk:reward ratio is probably slightly better with the S9, but if you're only buying one miner then you might be better off buying the Avalon.  I say might because your break-even time will be based on the current difficulty, which is likely to rise in the current months, making efficiency more important to get any significant profit.

There's people that receive completely broken miners from repairs, and then there's getting absolutely nothing from repairs back. I'd go with Avalon for sure because even though the breakeven time is going to rise, that's also going to happen with the S9. The reality is it does with all coins and all mining and if you can't deal with it, don't mine.

I have owned more than a dozen of S9 and T9 so far and never had any serious problems with them. the S9's sometimes were a little bit glitchy but once I figured their "tempers", they have been working well for me since. All of my rigs now have records of running months straight without needing any attention or maintenance.

I don't have any experience with A7 so far. Their reputation appears to be quite good but the profitability seems to come down to low end.

A word of advice for OP is to research *properly* on any of these products. People and opinions are always tend to be bias. If one only looks into a S9 service or complaint thread, all you would likely see are to be groans, however that does not justify a claim of "90% of shit". And some errors could indeed be caused by miner's negligence: static discharge etc. Well, I had burned a known-to-work S5 with a new cheapo PSU. I cried shitty S5 for days before finding this cheapo PSU fried another S3. At the end, I still yelled it was the damned PSU ruined my profit. But, indeed, was stupidity involved? Of course, but I could just never tell.

Just my two cents.

The A7s are cheaper to compensate for the lower efficiency, and they are indeed as reliable as they claim. They're also decently quiet, as I have a bud who runs one in the basement and it's essentially quiet with the TV running. As for PSUs, a good Dell server PSU is nice, quiet, and reliable as long as you also get a decent breakout board and wire the pcie wires right. They're also fairly cheap even with wires on, I bought a 1000w Dell PSU with eight PCI wires for $30 negotiating with a guy on eBay.