I can second that the transformer is a bad idea.  A few years ago we had a packing machine for another business that was setup for 220v but there was no way to pull a line to the machine because the commercial space leased at the time had a breaker box that was ancient and wasn't worth updating.  We tried this step up transformer box and it worked but it was very faulty and sporadic.  In the end we ended up not using the packing machine and it collected dust until we moved to another leased space which could accommodate  the wiring.

I think you sort of figured it out for me.  Three 741's on two 2400w PSUs.  On a 30 amp line which is easy for me to run from the panel and then use the 30A PDU that will safely hook the two power supplies up.

I've recently ordered 5 of the avalon 741 for October 16th shipping.

I haven't purchased the power supplies yet.  Was planning on ordering from parallelminer.  Based on the comments of it screaming like a jet engine, do you recommend using one per 1200w version setup  or should I order dual  2400w one.  I know its cheaper to purchase the dual 2400w one, but of course there must be plus and minus to this.  Any suggestions?

Are located in South Carolina?  Depending on prices I may be interested.

How many do you have?

Nice setup.  If you want to free up some airflow, I'd used the cheapo filters.  You know the blue ones at home depot.  The white pollen filters restrict alot of the airflow.  Just an idea to help with airflow issues.  You can swap them out more often and buy a bunch to keep handy without breaking the bank.

Thats the first I have heard about the parallel miner psus.  Noise wise not a big issue as I am installing in an area that is accustomed to fans and noise through out most hours of the day.  Its going to be on the second floor of a hotel next to the laundry facilities and maintenance room so there are always washing machine and dryers in use along with plenty of ptac units constantly running throughout the property.

Did you ever find out if the intake fan is necessary?  Just wondering as I'm doing a similar setup.

I would be interested in this as well on the correct operating temperature range...

Would you mind posting a picture or two of your outside setup?  I am in process of getting things ready as I have my own little project to build out for.

You can reference what I am working on in this link.  phillipma gave me tons of great advice. 
https://bitcointalk.org/index.php?topic=2200357.0

I think the PDUs will help give a cleaner look.  Also easier than running 14 plugs throughout the room. Thats alot of power cable running around. But you helped me clear up my misunderstanding of amps.  Will for sure to seek low AWG thick cables.  Thanks.

I agree on the 4- 1600cfm fans. 

I am looking into this fan in particular.  Trying to find some reviews on its quality and noise.
https://www.hydrofarm.com/p/VTX16XL   if this thing is correct it says 4515 cfm.  What do you think?

Prices ranges greatly especially depending on where I order from. 

Apologize for upsetting you with my extremely overpriced purchase of PSU from bitmain.  I see now exactly how overpriced it was especially after you add in shipping and customs fees.  Whats worse is I actually had parallelminer page bookmarked but forgot about it.  Man do I feel like an idiot.  But I think I will end up getting the parallelminer psu.  Just watched video of the psu and I like how it displays the voltage.  This will most probably be purchased tomorrow.  Plus it details exactly what plug I will need and will work with the PDU I just purchased. 

The wind tunnel idea is absolutely amazing using the car insulation.  I actually have the exact same racks already like your picture, but mine are bit taller, but they can be shortened and adjusted easily.  The car insulation material is perfect.  I think it will be a hell of a lot better than sheetrock.  I was worried about dust whenever I would do work putting holes in the sheetrock.  Would have to shutdown, cut, clean, shop vac and mop to get all dust out.  This would prevent that.  Plus so much more flexible. 

Thanks for you advice.  Really appreciate it.  Didn't expect so many responses that quickly.   

I just purchased 4 of the pdus at your recommendation from the link you sent me.

I will research these, but already see the savings you are talking about.  I may just get these instead to keep things more organized and tidy and either take slight loss and sell the Bitmain PSU on ebay or trade it to another member at cost.  No big issue there.  Easily can be fixed.

Hey everyone.  Great forum here.  I'm new on here, but have done a little P2P trading etc and have been pondering mining for a while.  Almost posted this in the bitcoin section but caught myself.  Hopefully its properly posted in the Altcoin section where it belongs.   

I've ordered from Bitmain 12 D3's and 2 L3+.  Respectively I've also ordered the power supply units for each unit.  12 of the AWP3++ for D3 and 2 of the L3+ AWP++. (I know I could have powered the two L3+ using one AWP++, but I figured it would be smart to have at least one spare, in my experience one is actually not even enough to be 'spare')  I don't know if I was lucky or not,  I believe I am part of the late November batch.  I know difficulty and all going up might never see ROI for months (if I do see ROI), but I am learning and this is all part of it in the long-run for me.  In learning I found GPU mining and ASIC mining.  See how I'd like to get my feet wet, I've decided to do ASIC mining first.  I'm a tinkerer so I like to try new things.

I have a room that has two large windows and dimensions are 7' x 7'.  Essentially a box with one side windows, two solid walls, and one wall with a door.  The ceiling height is 8'.  The interior of the room is open to any design I'd like it to be.

I also have access to two PTAC 12,500 BTU air conditioning units if I need.  From what I understand it is very hard to cool, but most important thing is to exhaust the heat.  My understanding is each unit is exhausting ~250 cfm.  So at 14 units that is 3500 cfm of heat to exhaust.  My plan is to build a 'hot box' in the center of the room.  Put two wire shelves (my so called 'racks') on each side of the 'hot box'. ( The plan is to do one side with ASICS and within next 4-6 months do the other side with GPU mining.) Build the back walls right up to the rack and without any attachments cut holes for the miner exhaust in the drywall.  ( I think drywall will be best because of its fire/proof/retardant ) .  Inside of the hot box put one,two,or three(not sure yet)  fans that will exhaust the heat directly to the outside.  No ducting etc, just two fans directly in the  windows pulling air directly out of the 'hot box'.  The power is available at this room already.  There is a quantity of 2, 300 amp panels downstairs that just has to be moved upstairs.  These panels used to power a hotel.  Long story short we have demolished one half of the hotel so we not longer have any use and they are currently disconnected.  If I had done some research a year ago, I wouldn't have demolished the property instead just shuttered it and use the rooms for one miner in each lol.  I have local electrician contacts that can accomplish this for me.  I plan to have the panel installed inside the cold section.  I think I have read too much and sort of confusing myself so posting this here so maybe I can get some guidance from the senior more advanced members here.  I am confused on the amps per unit and the 20% rule.  A little help definitely appreciated.  Okay I'm asking for a lot of help, but I promise I've done a lot of my homework.

Here is where my questions sort of start. 

What is the most efficient way to have the electrician wire up the plugs?  My understanding is that I should use 30 amp  220/240 breakers  with an  l6-30r plugs and 10 gauge wire is ideal. 

How many outlets do I need setup?  (this is where I was confused with PDU, amps, and 20% rule) I want it to be safe.

Is this the correct PDU I need and if so how many?  http://www.ebay.com/itm/Genuine-HP-EO4501-Server-Power-Distribution-Module-228481-002/232449268221?

Wanting to confirm that the wall outlet for the PDU needs to be these and how many will I need?  I think I could figure this out but have confused myself reading on the amps and 20% load issue.
http://www.ebay.com/itm/Pass-Seymour-locking-receptacle-L6-30R-MADE-IN-U-S-A-30-amp-250V-twist-lock-/390917364485?

Wanting to confirm that from the PDU to the Bitmain PSU's I will need these cords.  Seeing as how I have 12 PSU's coming I assume I will need 12 of these?
https://www.monoprice.com/product?p_id=24206

What is proper way to 'surge protector' these?  My electrician contact told me there is a box he can install inline with the panel that will help for surge protection. 

In my hot box, there will be 3500 cfm exhausting into it.  I assume I need to move at least 3500 cfm with a fan.  My question is does it matter how big my box is and what output fan I use?  I'd like to keep it aesthetically appeasing as it is a property that is still in business.  I've seen these quiet vortex fans that move lower volumes of cfm, but I was not sure if the heat build up would feed back into the miners.    I could always use more of the lower volume fans to get to at least 3500 cfm, but if I want to future proof it for GPU mining as well,  I may have to bite the bullet and put in the big wire cage fans that move 5000-6000 cfm.  Also for inputting air into this room, do I need to actually put fans inputting just as much cfm?  Or can I just put a grill with dust filters to allow natural suction in.  I do have spare ptac units available that are rated at 12500 btu each.  Easily can have those installed if one thinks that will help. 

As for my electricity costs they are actually decent at .10kwh and .12 kwh during peak.  Though fortunately for me the hotel is absorbing the electricity costs so its sort of a win/lose for me.  The power bill for hotel is already high so its just a bit higher in retrospect.

I'm open to all other suggestions as well.  I could just ship them to cohosting location, but honestly that takes the fun out of it for me.


Thanks in advance to those who made it this far reading.   Extremely thankful in advance to those who take a moment to see what crazy endeavor I've gotten myself into.  There is a lot of great information on this site, and only hope to read and learn more.

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Please message me with what you have and what your asking.

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