Bitcoin Forum

I'm very new to mining and its about the time of year i upgrade my PC and i was looking into
building a dedicated mining PC.

Here are the proposed specs:

AMD Phenom II X6 1100T
Gigabyte GA-990FXA-UD7
8GB Corsair DDR3
Powercolor Radeon HD6990 4GB x2 maybe a third later on this year
Silverstone Strider 1200W Gold
Most probably running windows 7

inc HDD and Case it comes to around $2500 Australia Dollars

I would like to know how profitable mining would be with a rig like this?, would it be better to mine
in a pool or solo mine ?
What would income figures look like ?

Thanks,

Hey,

IMHO your proposed rig sounds way over specced for a dedicated mining rig! If you use it for gaming as well as mining then OK, but as a dedicated rig its probably a waste of money.  :P

I spent £380 on a dedicated, low power rig with the following spec:

CPU: Sempron 140 (cheap and draws very little power)
Mobo: Gigabyte GA-870A-USB3 AMD 870 (x 4 pci-e slots, includes 1 x16, 1 x4 and 2 x1 slots)
PSU: 800W Corsair GS800 (decent power supply a must, this one is 80% and relatively cheap)
Memory: Corsair 2GB DDR3
HD: Seagate 1TB 3.5" Sata-III 6GB/s Barracuda Green Hard Drive - 5900RPM (low power and cheap)
GPU: Two XFX ATI Radeon HD 5830's (picked these for £71.99 each new, not the greatest GPU but gives the best £ to performance ratio of all GPU's)

This set up gives me around 650 MH/s and produces around 0.45 BTC per day at current difficulty running 24/7, with the option of adding 2 more 5830's at a later date (when I have abit more cash handy)

As for your mining options, would recommend that you stick to a pool as solo mining is somewhat of a gamble unless you have hundreds of GH/s at your disposal. A pool will give a much more consistent payout, my recommendations are www.bitcoins.lc (http://www.bitcoins.lc) (0% fee but bitcoin payout can be a little erratic due to them having a lower pooled power of around 500 GH/s on average) or www.btcguild.com (http://www.btcguild.com) (they have around 3,000 GH/s, more pooled power = more consistent payouts)

Good luck!  ;D

*Edit - the CPU I meant was an Sempron 140*

So now I'm guessing CPU and memory doesn't have much to-do with mining,

Well i can do a dedicated low power mining rig like yours,

Athlon II
2gb DDR3
4x 5830s
850W Sliverstone

for around $1000 AUD so less than half of the one i proposed earlier.

Would that be more economical or would cutting down on the CPU and memory of the previous and use
6990s be more economical ?

Hey noogia93,

You are right – CPU and memory don’t have much bearing on mining , they just tend to eat power.

I’ve found the bitcoin wiki particularly helpful when making hardware comparisons. https://en.bitcoin.it/wiki/Mining_hardware_comparison (https://en.bitcoin.it/wiki/Mining_hardware_comparison)

According to the wiki, two 6990’s will give you around 1,340 MH/s and draw 692 watts before any under / overclocking. Four 5830’s would give you around 1,000 MH/s and draw 716 watts again before any under / overclocking.

I think a 850w psu should be enough, but you may want to step up to 1000w, just in case, up to you.

I haven’t actually gone for the four cards myself yet, I understand that they require a pci-e riser to connect to the 1x slots in my mobo, along with 8 pci-e power connectors on the psu (or Molex to PCI-e power adaptors). Perhaps someone on this forum with a four card rig can help a couple of newbies out?  ;D

So your choice is to pay more for the two 6990’s (and have an easier set up) or to go for the (cheaper) four 5830’s (but potentially a trickier build)

Hope it helps.

I do agree on the 2x 6990 (vs the 4x 5830 build - given you already have the cash to buy dual 6990s) - plus you can probably add 2 more 6990s in later for your 2x 6990 or sell your cards for cash/run them in crossfire for good gaming performance..

5830 build is more for entry/low budget rig (or for people who do not have the cash to buy 6990)

Or people who don't want to waist their money. You get the best megahash per dollar with the 5830 people don't seem to realize this.

Hey koopa, does that motherboard have open ended PCI-E 1x slots? Nice board if that is the case!

Hi Maasu,

No, unfortunately the Gigabyte GA-870A-USB3 AMD 870 doesn't have open ended pci-e 1x slots. I could open them up with a soldering iron, but there simply isn't enough room to fit four cards next to one another on this mobo. Methinks I will have to use extension cables for the 1x's and stick the cards somewhere else in the case... if there's room. If not it'll have to be case-less.

Its not a bad mobo for the price tbh, paid £64 for it.

Cheers.

Agreed - the 6990 is roughly six to seven times the price of a 5830, but you only get three times the performance out of it. The 5830 certainly hits the sweet spot in the £ to performance ratio.

arrghhhh......... I'm so confused now..... The 5830s are really in the sweet spot, but the
6990s can be consolidated in one computer. I can setup 3 quad 5830 rigs for around $3000 AUD
giving i presume around 3000mhashes ? but for around the same price i can get a single
rig with 3 6990s which will not get anywhere near 3000mhashes

What are you thoughts go with 3x quad 5830 rigs ?

or

What are the chances of me detecting a block in a month with a triple 6990 rig ? or would 3x quad
5830 rigs be better ?

Does more consolidated power mean better chance ?

 

Get a cheaper CPU, amd dual core, only need 4 gigs of ram.  Get two of the ATI 6990s.  It will be end of july before you can get that card though, I am still waiting on my second one.  WIth one ATI 6990 I am getting 900 hash with the overclocked switch flipped.  I think this would be your better option and use less electricity then 3 seperate rigs.  Electricity is the profit killer, and if it gets too hard to mine then you will have a better resale value on the 6990s.

In a month? From what I have read unless your at a block per week (or 2 max) you should be in a pool.

What are the chances of hitting that amount of blocks ? or would it just be trial and error
and then move to a pool  ?

http://www.btcserv.net/bitcoin-calculator/

There is a calculator that can calculate "about" how long should take you to hit a block. Mind you there is always luck but it gives you a general idea.

I've tried 2 calculators and they say it will take approx 40days to solve a block solo,
that means every 40 days 50 BTC ? would that be more efficient than pooled mining ?

I think it basically equates to be around the same amount of BTC per 40 days

What do you guys think ?

don't do solo mining that says 40 days but it could also take 80 days. Plus we don't know what the difficulty will be in 40 days.

ok then, thanks for that

It is basically the same if you pool maybe minus 1 or 2% from fees from the pools.

The only reason I can see to not pool mine is for security.

edit: also, 40 is just the expected value. It could very well take you 2 minutes to win a block but it's very unlikely.

at what hash rate would solo mining become effective ?

It's more of a question of how long you're willing to wait to discover a block. I'd say if you can reasonably expect to discover a block every 2 weeks then you're probably okay.

here's a mining probability calcuator. So yeah, we're looking at like, 5 ghash/s to discover in 14 days on average.

see this is where i get a little confused. When you/we say that at 5ghash/s would discover ever 14 days
is that one machine at 5ghashes or say 3x 1.7ghash rigs. To lower the discovery time does one need to
cluster rigs ? or is it just having that performance under your belt that increased your chances ?

Are multiple computers supposed to be linked together so they can crunch through the work altogether ?