5 months is crap: Two points to consider: Your Calculation is based on a constant difficulty. Look here: http://bitcoindifficulty.com/ and make your own guess on how hight difficulty would be in 5 months.
Second: Break Even Point is not the Point when you get your hardwarecosts back. Break even poin is much earlier: When you have mined that many coins (and exchanged them) that you would have no profit and no losses AFTER Selling your used Hardware you reached the break even point. That would be after mining 25-35% of the original value of your rig. Everything you mine after that is profit as you can always sell your parts..


Your build seems fine. Perhaps use a cheaper Mainboard: For two cards: ASRock 970 Extreme3. For three cards: ASRock 970 Extreme4. And I don't know how good XFX PSUs are. Corsair or Seasonic are very good ones.
Maybe this one: Corsair Professional Series HX750 80PLUS Gold 750W or this one: Corsair Professional Series Gold AX850 850W (three GPUs)

Just to be curious: Do you have the HAF X or the HAF XM? 199$ seems a bit to expensive for the XM. But I don't know prices in US. In germany I would pay around 90€ which is around 120$. Also the HAF XM supports only 3 200mm Fans, whereas the HAF X (its big brother) supports up to four.  But it doesn't matter.

Four 200mm fans are good. I think 3 of the fans are provided with your case. So you need one other: Look Here: http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=100007998%20600035599&IsNodeId=1&name=200mm And choose one with a High Airflow Value. E.G.
NZXT FN-200RB 200mm Case cooler - 166CFM
BitFenix Spectre Pro LED Red 200mm Case Fan  - 149CFM


The installation is quite easy: The fan is provided with 4 screws. Just Use them to install it at the sidepanel of your case. Only thing that matters is the direction in which the cooler blows: I would suggest taht it should blow into the case directly on the hot grapic cards. I don't know exactly how to explain it: Each fan has one side which is rotating and one side which holds the motor. This side has 3 or 4 small Bridges(??) going from the middle to the outside. That is the side where the air comes out. Install it in a way that this side is orientated to your graphic cards.
The electric installation is also quite easy: The Fan has a plug which can be connected to a HDD powercable from the Power supply. Just plug it together.   Perhaps you can also plug a different connector from the fan onto the mainboard: You don't need to if you can plug it directly to the PSU (Powersupplyunit).
BUT BEWARE: NEVER EVER PLUG IN MORE THAN ONE CONNECTOR FROM THE SAME FAN into ANYWHERE!
 

@ superdork:
You can bring your Watercooler back right away. This would cool a CPU, But as you don't use your CPU for mining, it won't produce any heat. All the heat is coming from the GPUs. It is very expensive to buy new coolers for them, as you would need a very big Watercooling Station for that. You just don't want to even consider it. Building a own watercooling system is highly complicated for someone who wants to build his first PC (which is indeed easy) Just use the Boxed Cooler that comes with your CPU. Nothing else. If you want to invest money in cooling, and i strongly advise doing so, then buy some fans AFTER you chose your case.

If you want a case without mods, then buy one with at least 8 Slots for expansion cards at its back. http://extreme.pcgameshardware.de/attachments/542846d1335644093-tagebuch-grosses-update-sharp-system-7700-endstufe-als-neues-gehaeuse-20120427_174249.jpg. When you look at this picture, you see seven small Slots, two covered with a sort of mesh. Just beware that your case have 8 of it.

Good cases would be:

Corsair Carbide Series 500R
Cooler Master HAF XM
Rosewill THOR V2 (a shame that I cannot buy this case here in germany. It looks shiny)

Both are ready to install a big (200mm) Fan in the Side directly above the GPUs. They also are ready for many more Fans which would blow in fresh air from the bottom and the lower frontside, and blow out the warm air on top and on the upper backside. For Sure there are other good, maybe better options than these. The suggested Rosewill THOR V2 looks pretty nice with its 3 preinstalled 230mm Fans. Take it.

I would suggest a case with at least 8 PCI Slots on the back. This Lancube has only seven. Yes it is true that slight modding should enable you to build all cards in, but as far as I see that means to Cut pieces out of your shiny new case. I did that too with an old case, but for my new miner odered two days ago, I chose a suitable tower which doesn't run into that problem. I chose the Corsair Carbide 500R Series Tower, but I am not sure if that is the best choise. Maybe the Coolermaster HAF, or the suggested Antec is better.

But of course the airflow in that Lancube seems very tempting. So If I would bother to mod my own case I would definitely give it a try.

@ nemesis: Your Case looks cool, but it won't take a third GPU in the lowest Slot because therefor it needs 8 PCI Slots.

The next point about the Mobo is also wrong. On Both Mainboards you have 2 GPUs in direct neighborhood and one seperated by one space from the others. So where is your point?

This looks good:

http://www.maximumpc.com/article/features/video_how_build_pc_ever_step_explained.

This guy tells you should work on a metal workbench, because of static electricity. For me it was always enough not to wear fleece clothes and touch something grounded in my house, before going to work.
I am sure that you can find many more of this videos if you google for it.

And
+1 to salihno71. Heat will be for sure your biggest issue. So be sure that you get some of the most powerfull fans you can find.

G: Wifi is good if the connection is stable. When you loose the connection, you will loose mining time: Less Coins

H: They are right: On cheaper Mainboards, there is almost only one PCIEx16 Slot which is also electrically connected as a 16x Slot. The other ones are connected as 8x or 4x Slots. Maybe only as 1x Slots.  That is a big issue when you are gaming. Although you can put a x16 Graphiccard in a Slot which is only connected as 1x, it is much slower then. But in contrast to gaming, you don't need that bandwidth for mining. Many people here have their cards connected to a PCI-E x1 Slot with a riser Card. And it works well.

I: That is also true. But as you don't use that Computer for daily work, it doesn't matter. You just start it once and start your mining software. With a normal HDD that may take longer than with a SDD. But only a few seconds. After that: Everything needed is loaded and HDD Speed doesn't matter anymore.  The real magic happens in RAM and on GPU.


To your selling Argument: You won't sell that system in a whole to someone other than a miner. Because no Gamer needs 3 7950 Cards. Here in Germany you mostly get only 70 to 80% of the original buy price if you sell something used with all accessories and original package. I think that is nearly the same in the US.  So calculate: You want to lose 25% of 200$ (cheap HD, CPU + Board), or do you want to loose 25% of 600 to 700$ (expensive Solution). Also your rig pays of faster if you don't buy the premium components.
My point is: Your miner would perform the same with the premium components as with the budget components. If you save now 600$, you don't have to bother getting them back when you sell your rig. You can throw away the cheap components by then and although have more money than if you sell the high price parts

If you intend to use it after mining for working or gaming in a few months, then it maybe is better to buy the good parts, because then you only have to sell 2 7950 Cards for having the perfect Gaming Rig. But also in this case you can do yourself a favor and buy a cheaper Intel Motherboard, for example the MSI Z77A-G45 Thunderbolt, which is also over 100Bucks less than your serverboard.

Ah thanks, that helped it alot.
Now my 7950 works. But I cannot change the gpu settings for Overclocking. How can i fix that? When i go to [G] for GPU Settings, then I only can cange the Intensity but [C] Change settings is not shown anymore. cgminer is also unable to read GPU temperature and fanspeed.

Edit: Adding --gpu-engine 1000 doesn't change the Hashrates also (I tested it yesterday and it should do so)

By the way: i encountered a similar problem on my Linux Rig when starting cgminer in a screen session. The Problem was that no X-Session was available to screen. After solving that issue everything worked well. But I have no clue how to solve this in Windows.

My actual commandline:
 --scrypt --gpu-platform 1 -o stratum+tcp://coinotron.com:3334 -u *** -p ***  --thread-concurrency 21712 -I 18 -g 1 -w 256 --gpu-engine 1000

And here my cgminer -n output:

Hello,

a few remarks from me:
To A:
As a pure mining PC your configuration is way to expensive. Mining is done via GPUs. You don't want your processor to mine, because it is way to inefficient. So you can save a lot of Money:

- Intel Box Intel Core I5-3570k
+ cheapest Celeron Processor you can get

Use the provided boxed cooler for your CPU as it won't have any load during mining.

The Harddrive is also absolutely unimportant for mining, because you start it once and, in ideal case, never shut it down anymore. If you run Linux, a USB Stick is enough, if you run Windows, a small Notebook HDD is enough. You have absolutely no need for a SSD.

- Samsung SSD Pro840 256GB
+ smallest+Cheapest (80GB or more) HDD from Store

The Motherboard is nice and expensive. One of it's unique features for minig is the fact that it has 4 PCI-E x16 Slots with a free Space between each of it. Yo you can install 4 Graphiccards directly onto it.
If you only buy three, you don't need such a powerful Mainboard. Then you could also use this combination: ASRock 970 Extreme4 + Small AMD Sempron Processor for around 100 to 130$ in combination.

-Intel CPU
-Asus P8Z77

+ASRock 970 Extreme4
+Small AMD Sempron Processor

16GB of Ram are also absolutely overpowered. 8GB should be enough fpr mining litecoins. For Bitcoins and any other Sha 256 cryptocurrency 2 GB is sufficient.
By the way: I hope you orderd the Three Fan Version of the Gigabyte Cards.

So Alone by removing the SSD and both the expensive Board and CPU you can save up to 600$ maybe more.

To B:
I know many here says that a case is like venom for a miner. I disagree. All my miners are in closed PC Cases in an air conditioned room. Coolermaster HAF is one of the best ventilated Computercases you can get, so go along with it. But to add point D: Buy more Fans. The biggest as possible for your case. (Think that is 2 200mm and a few 140mm Fans), and don't buy silent Fans. Buy big loud and powerfull fans with much airflow. And under no circumstances store your Rig in a Closet. That would only hinder airstream and cooling. Look for a free space where a bit of noise doenst matter and which can be ventilated with the outside.
Just to compare: My rig with 4 5850 Cards brought my Room from 15°C to over 45°C in one night of mining.


E: Easy: The more you overclock, the warmer your rig gets. Using cgminer, you can adjust that very well.
F: Nope. A Miner is like every other internet computer in your home. So that should't be a problem. 

KJ

and how would I do that exactly?

Yes. I am using AMD APP SDK  2.8 and Cataclyst 13.1 When I use the 7950 as primary device without the IGP, than cgminer works correctly. It only fails when using the IGP and starts mining with that instead.  (Running under Win 7 64bit)

I used a dummyplug. It is needed for windows to simulate that another monitor is plugged in. Otherwise the card would be deactivated.
But it didn't work. I was able to start to Windows, but cgminer doesn't detect the 7950

Hello

i have a small problem with my CG miner.

My System: ASRock Z77 Pro4-M
Intel i5 3570K
XFX HD7950
Win7 64 Bit
AMD APP SDK 2.8
Cataclyst Driver 13.1

Following Issue: I want to use this PC also as an office workstation. Therefore I don't want mining to cause an input lag on the screen. My idea was to work over the IGP of the CPU while mining with the GPU. No I set the onboard Grapics as primary grapicsadapter in bios, but after booting the cgminer only detects the slow onboardgraphicsport. I also used a dummy plug for the 7950 to imitate a second monitor. What am I doing wrong?

Best Regards

KJ

Hello,

I am wondering if it is possible to use the IGP of a Sandybridge Processor for the monitor picture, while having a 7590 in a PCI-E Slot available for Mining. How would i do that?

KJ

Die Fragen nach der Solaranalge versteh ich nicht. Ich mein wir sind in D. Da gibts ein EEG. Kauf dir ne Solaranlage und du bekommst Geld für dein eingespeisten Strom. Und noch mehr Geld für den selbst verbrauchten Strom. Ich glaube nicht das der Threadersteller hier ne Hobbyanlage meint. Da erübrigt sich auch die Frage nach der Nachtspeicherung. Das Puffert der Versorger.

200 to 300€ is a hard limit. I would say you need at least all PArts for a normal PC. This would be around 150-200€  (30 CPU, 20 Ram, 30 Case, 50 Mobo, 50 PSU). That allows you to spend 100 to 150 € for Grapiccards (180 if you spare the case). I think ypur best bet wpould be a AMD HD7790 for around 120€ which should make around 300MHash/sec when overclocked. For Litecoins, the 7790 may not be optimal. You could try to grab a 6950 and flash it to a 6970 which give around 350 to 400MHash/sec. That should be better than the 7790 but costs at least 180€. Or you spend another 60€ and buy 2 7790s for a total hashing power of around 600MHash/sec.

I totally disagree with you. The ROI of such a machine would be perhaps 2 month or so. You have to take into account that, unlike ASICS, these GPU Miners are not a one-way investment. Yes you are right: You spend 4000 Bucks for hardware. If you make 9 BTC in the first month, you would have around 1500 bucks at the current price. Even if you need to month for that goal, you can easily sell these cards to other miners or, what is more important, gamers. There are always enthusiasts who pay 80% of the original price for used GPUs. So you would get around 3000 Bucks from your 4000$ investment. That makes it profitable very soon. And from that break even point you can decide each time to sell the hardware. Luckily bitcoin mining is actually much faster than decrease of your hardware value.

Just my 2 cents.

KJ

Lol... i tried to transfer 40 EUR from Germany to my Intersango Account. Result: My bank account locked.
The Bank says that the Intersango account was used for illegal transactions and fraud activities before and that it is therefore under an embargo. They canceled my transaction and locked my own bank account. Just in case a trojan horse or a phishing website had taken it over.

Any similar experiences?

ich selbst betreibe die Kombi mit einem 850W Netzteil. Mit OC brauchts in etwa 800W Ohne OC ca 650W.

LG

Ein Corsair AX850Gold hätt ich. Würde es abgeben wollen da ich gerne auf eine günstigere, weniger Energiesparende Variante zurückgreifen mag.

LG