I started a small farm! I have been building it this week. This is what i've learnt.
I now make £1260 per month. I spent around £3225.
I get free electricity included in my industrial rent so that wasn't a concern. My goal was the quickest possible ROI. I got it down to about 10 weeks to recoup 100% of my costs with this method.
Album here: http://imgur.com/a/xj449 (note this was before completion, just the first rack was done. Some detailed changes were not yet made). SoftwareThis is what you want to install on your hard drive when you set up:
I've been running clean installs of Windows 10. I tried linux, but unless you know what you're doing everything just takes 10x longer while you figure it out. Stick to Windows 10 if you're new. You can get windows from M$'s website, create a bootable USB, and install. When it asks for a product key, just tell it you don't have one and then install Pro. If it ever demands it you can buy them on ebay for ~£15.
Once installed, install the various chipset drivers, along with the AMD drivers. Using the right drivers DOES make a difference, so use the recommended 15.12 (make sure you uncheck the auto-update it asks for at the end of the install). If you're using RX4* series cards, you'll have to use newer drivers.
Claymore's miner (versions 12 and on) and Optimer (versions 1.6 and on) are both great. I think Claymore produces higher hashes overall. Use one or the other.
Claymore talks about putting in Environment Variables and setting the virtual memory, but doesn't explain where to do this. Right click the start icon, choose system, then advanced system settings. The virtual memory is under Performance settings, and the Environment Variables are at the bottom of that box. Once youve opened Environment Variables, click New under System Variables, set the Variable Name as per Claymore's Readme, and the value as the number he gives. Then Ok when done. If i'm honest i've not noticed this making a huge difference on my systems. Also in windows add the miner to the startup list so you don't have to do it after a reboot, and change the power options to HIGH PERFORMANCE so it doesn't set the computer to sleep after half an hour of mining!
For remote access, use Teamviewer. It's simple and it works. That way you don't have to have a monitor etc. plugged into every rig.
HardwareGPUs I went the route of buying cheap GPUs on Ebay or other used stores. I got about 15 R9 280X cards for an average of £70, and a handful of 290x for around £100. If they don't work, you can return them so who cares. Cards the seller claims are artifacting almost always hash fine. Cards with bad fans are easy to fix (take the bad fan out, strap an 80mm fan on instead with some cable ties). Buying cards with irrelevant defects will save you a fortune. You can also find some great deals by just watching ebay for auctions ending at bad times (I got a 7990 for £140, and a Pro Duo for £370. That's 1.6KH right there, in just two slots.) I think these cards will loose no more than £20 value/year, so you can always resell them when it's time to upgrade. Note that 280X cards are power hungry. I can't expand the farm because i'm using all the power I can get without pushing the wiring too far. That is the only major flaw- to go bigger i'd need to use lower power cards.
PSUSWhen people say on here that cheap PSUs are a waste of time, they're right. I tried those 1000w on ebay for £30 PSUs. They both broke after running a single 280x for about 2 weeks. Utter garbage. Then again I think the £180+ 1000w brand name PSUs are also a waste of time and a hard to resell. Brand name PSUs hold their value very well so are a fairly safe investment. I like PSUs around the 750w/£60 mark from the half decent brands (Cooler Master, Antec, EVGA). Yes you need 2/rig, but I'd rather have 2 PSUS per rig for a total cost of £120 than one running £180 or more. It also means you can keep hashing at half speed if one breaks, and they are easy to sell on Ebay later for just a little below retail, so also very little risk of value loss.
Motherboards & CPUsMotherboards and CPUs loose value faster than GPUs and PSUs, so I think you want to be careful here. You also want as many PCIE slots as possible. But the big 6+ slotter motherboards are now all £120 plus, often £150 or more. Give it a few years and they will be worth 1/3 of that. I went with the ASUS H81M-PLUS giving 4 slots for around £50. Stick a celeron in there for about £25, and a stick of cheap DDR3 (at least 2GB) and you're good. The cost/slot here is fine, that's all you're really interested in.
HarddrivesI made the mistake of going for cheap ebay 80GB HDDs for £5 each. That was the biggest mistake i made in this whole project. I invested hours into install windows and drivers onto hard drives that then died outright, or were PAINFULLY slow at the desktop. Either buy £25 60GB SSDs, or NEW 80GB mechanical. Don't go cheap here, it will drive you nuts later.
RisersGet the good risers on ebay, they should be about £5 each. There is a cheaper version than that, the ones without the little PCB board at the base of the slot- but I found those had a very high failure rate- and were a short circuit risk.
Molex Adaptors ETCI found a website called
http://www.kenable.co.uk/ which if you're in the UK does some really handy stuff like Molex>8pin adaptors for very little money. Quality seems okay.
CasingThose metal cases people are selling for £100+ are a stupid idea if you want to make your money back fast. I used old wooden ikea shelves we had laying around. Use whatever you can find. Plastic tubs look shit, but they work. Plastic or wooden shelves are where it's at!
CoolingI went to Wicks and bought 10 lengths of wood for £11. I built them into a large frame (95x85x160cm) which sits around the miners. It is wrapped around the sides and top with bubble wrap to insulate and keep the heat in. There is a 3m plastic tube duct (£7 from amazon) which goes into the top of the frame through the bubble wrap, which extracts the warm air (I happened to have an in-line cooling fan, but those can be expensive) and pumps it out an open window. Cooling sorted. Otherwise the room does cook.
That's it! I hope that helps somebody.
Cost break down:
15x 280X £1050 4200H/S
3x 290X £360 960H/S
2x Dual GPUs £510 1600H/S
5x mobo/cpu/ram/hdd £575
10x PSU £600
20 x Riser £100
1x Misc £30
Total: £3225
Return: £1260/month.
