Bitcoin Forum

Hello, fellow forum members!
I was planning to get into GPU mining but now it's pretty much obsolete.
I am still going forward with my rig but I will mine other coins.  Here's my proposed setup, how does it sound?

Rosewill Green Series RG530-S12 530W
about $55
Is this a good power supply?

2GB of RAM

4x AMD 7950 GPUs
about $320 each

1x AMD A10-6800K “Richland” APU
about $150
GPU and CPU!

1x 4 slot motherboard
about $130
Which one?

12x 100 Watt Solar Panel
about $200 each
(for a 1200 Watt power supply)

You're probably going to want at least a 1200 watt power supply for 4x7950
Also you can get away with a really cheap Sempron for CPU.  I think a Sempron 145 is ~$40.

Well the Richland can act as another GPU as well, so I was told that it was better than just a cheap CPU.  :)

I'd check the estimated mining performance and power consumption of that before settling on it.  I don't have any experience using those AMD CPU/GPU processors for mining but feel like they may not be worth it.  That's simply my feeling though and not based on any research so you may be right.

Well, I got the suggestion from another forum member.  Who knows?  :)

What's the solar panel for? You will be running 1,000watts or more, a 100watt solar panel won't power it..

Don't bother with the APU, the GPU in them won't mine for shit.

2GB of RAM is good only if you plan to mine bitcoin, for scypt coins you need more RAM.
You can buy that processor only if you want to use your rig for not-only-mining purposes (internet, video etc... ) Then this integrated GPU is perfect

How much RAM do you think I will need for scrypt coins?  For now I will change it to 4 GB.
By the way, I have edited the post.
12x Solar panels

Key question:
Which motherboard?

don't bother with solar panels 4 7950s use between 900 and 1200w depending on the brand of the cards ( i use 950w at the wall maximum )

if you give me a list of questions i will do my best to ancer them  :)

Are you kidding?  Skip the computer, just buy the panels.

The return is much better. Guaranteed 400%-500% return on investment over 30 years. 

How much will a rig make?

my hardware as paid for its self nearly 2 times over in 3 months ( 83x 7950 vapour x cards ) electric costs £0.14

No pics of your setup in your previous posts?! Outrage!  :-\

You're going to plug a solar panel directly into your GPUs, and have them power the GPUs, bypassing the PSU? You'd have better luck making a snowman in hell.

1) PSUs are very particular about the voltages they put out. The difference between a good and bad PSU is determined by the micro-ripples and variances a PSU gives off under load. A solar panel giving off 12V plugged directly into a GPU isn't going to be terrible in that regard, and your GPU prolly won't run stable.

2) Solar panels are only good if there's sunlight to power them. What are you going to do at dusk/night?

Well, if you are short on money and can only start with one GPU card, then the 115 MHash/s SHA256 / 70 kHash/s scrypt of the APU  is a nice extra. But if you have the money to get 4 7950 that will give 2400 Mhash/s SHA256, then it isn't much extra. Then I would look for a low power CPU instead, because the GPUs pull a lot of power already. APUs are nice when you want to build up a mining rig over a longer time.
For Scrypt you should have the same amount of RAM as your GPU cards, so 4x 3GB = 12 GB. I would say 16 GB should be good as the operation system and the mining software also need a little memory.

You have 3 options usually with solar, depending on what is available in your location, in order from Best to Worst case in terms of profitability and ROI:

Best: You feed all of your solar output directly back into the grid without consuming any of it yourself on your consumption meter. Your government or municipality pays you for the kWh at a rate higher than your consumption rate. Eg for a while some friends in Australia had $0.56/kWh out while their consumption rate was $0.20 at the time.

Meh: You have some kind of smart metering system or load sharing inverters installed that has fully replaced your old meter or works in conjunction with it such that the solar energy you produce is 'subtracted' from your regular consumption. You do not really sell your energy to the grid unless you are consuming very little power, in which case you ARE paid for the energy you return to the grid.

Worst: As above in 'meh' except your excess solar energy production is NOT sold back to the grid, usually because your local power grid is already saturated with solar installations (a huge problem in Australia at the moment) and you could not get approval to connect your installation to the grid. *This could actually be a win for some bitcoin miners though, because you could time your setup to mine during sunlit hours consuming the excess solar power. Essentially 'free excess power for mining'. You would DEFINITELY want some very nice batteries on the DC side or some UPS units on the AC side to pull this off though.

Worst, with bonus points: You think you can run your GPU mining rigs directly with DC (!!!) output from the panels, OR, from the inverter but with no fallover from the grid or energy storage, so if you have a droop in voltage from the panels your inverter shuts down and your mining stops. I suppose that with something like raspberry pi and some very clever programming/fiddling or even a windows laptop that had some kind of triggering/monitoring from the real world (eg. arduino board) you could pull this off with ASICs or FPGA, set to turn on and off quickly as power comes as goes from the panels but it would most likely be a huge pain in the ass to do it on a large scale. The investment and ongoing replacement costs of batteries for DC side storage or for in UPS (for the worse scenarios) is substantial and should be taken into account when doing any calculations.

Where are you getting your info from as it regards to the RAM requirements for SCRYPT mining? Those figures sound absurd I have rigs with 3x 7970 in them with only 2gb of RAM and they mine just fine, mining with cgminer on scrypt doesnt use alot of memory as people keep talking about. Even 4gb is over kill as far as i'm concerned.

This should be your setup:

Motherboard: http://www.newegg.com/Product/Product.aspx?Item=N82E16813157262 $100

PSU: http://www.newegg.com/Product/Product.aspx?Item=N82E16817256054 $289 (After rebate)

GPU: http://www.newegg.com/Product/Product.aspx?Item=N82E16814202008 $309 (After rebate) (Same as 7950!)

CPU: http://www.amazon.com/gp/product/B0040BPHJO/ref=oh_details_o07_s00_i00?ie=UTF8&psc=1 $30

RAM: http://www.newegg.com/Product/Product.aspx?Item=N82E16820139077 $46


I know you wanted 7950's but right now the 7970's on Newegg are the same price, and they give you more hashpower/$.

However, you'll need a better PSU if you want to overclock (and the 7970s uses more power anyways), which is why I chose the 1500W.

It's pricey but you can use two smaller and cheaper PSU's if you know how to connect them.

Oh and also use powered risers just in case.

This took me a while to compile so I'd appreciate a donation ;)

7970s might get a higher hash rate but they use more power ( 7970 700kh 250w+)  (7950 630kh around 210w)

7950's use around 260W overclocked while the 7970 uses about 310W OC'd.

120 more watts is only around $13 more a month if your rate is $0.16/kWh and you get around 150kh/s more.

It's all personal preference I guess

my 7950s run at 1050 core 1250 ram 1.050v 630-640kh with a 3 card rig under 720w from the wall and a 4 card rig under 920w from the wall

Every card is different.

I have to OC my 7950 to 1350ram to get it to 580kh/s with 6% powertune.

lol I got a bad card I guess.

I get the same on all 83 cards give or take 1-2%

I'm building it in sections, over time, so I guess I'll keep the APU for the extra hash power in the beginning.

This is my first time building a rig, what are powered risers for?
Also I hear you need "heatsinks," what are they for?

Finalize, you have a devcoin address?

There is a usually unknown but still inherent limit to how much current a motherboard can - in total - pass to its PCI-e connectors.

A full-power-rated PCI-e full length slot by international standard can supply at least 75 watts to the card. This is not enough though of course for most good cards, so we have 6 and 8 pin molex to help supply more power.

The problem becomes, that if you are running a lot of cards then you don't know how much your motherboard can safely supply via PCI-e to all the cards. Maybe its just 75 watts? Maybe its 400? In any case it is a unknown and it is a risk.

The solution is to bypass some or all of the power connections via the PCI-e connector and instead use risers that have power connectors spliced on, so you can power it 'directly' from the PSU just like with the 6 and 8 pin molex connectors for the card.

This decreases risk of: random power transistors and capacitors and other parts on the motherboard failing due to overheating or worse, just exploding, and it arguably increases stability in the case that your motherboard can physically take the load but still supply insufficient current.

There are threads here about users who have charred components on their motherboards or melted/charred the main motherboard ATX connectors or cables.

https://bitcointalk.org/index.php?topic=161242.0

https://bitcointalk.org/index.php?topic=102890.0