Mining Hardware Suggestions - Looking at 7850's for the first time instead of 79

[stepeato]

I just noticed the price gap, and think it might be worth it for me to go with a 5 card motherboard with can seemingly be found for around $180 or so, with five brand new 7850's (cost of about $750/approximate hash rate of 1.7 mh/s) -OR- two used 7950's for about $700 with a hash rate of around 1.2 mh/s. 

I am fairly new to rig building, and cryptos in general.  Would I likely be better off buying these slightly less powerful cards?  The power difference is negligible as far as I can tell, its about the same as two 7950's.

https://litecoin.info/Mining_hardware_comparison

Thanks everyone, I really appreciate any suggestions or advice. 

Also, you guys heard of poolwarz.com?  Looks like a great pool for beginners, from what I can tell, you wont have to setup config files and whatnot for each particular coin, could be wrong, but thought it was worth sharing with you guys.

[HellDiverUK]

7850 is slow as shit.  I've got one, it only does about 280kH/s.  Pointless.

[stepeato]

Forgot to mention, i'm building an scrypt rig, not sha-256

but with 5 of them running at say 280kh still = 1400kh/s total vs only a total of 1200kh with two of the best 7950's, which again, will have to purchased used to get both for under a total of roughly $900 right now.

Another thought I had, is that it may be better to have 5 cards producing the same amount of kh/s instead of two (given the power consumption difference is negligible) just in case a card decides to die or underhash, you have much less invested per card.  Has anyone ever acted on this logic?  any advice? 

also, are there any motherboards that are known to run five 7850's particularly well?  Any suggestions from the gurus out there?  Already have a 6 core amd 1045t, and the ram from a previous system, both of which I need to fit into the new rig.  I truly appreciate the help friends.

[Sondey10mg]

7850 is slow as shit.  I've got one, it only does about 280kH/s.  Pointless.

Than you have bad settings. I get 350 kH/s with ease. Reference model, stock speeds

[diddyfan2pac]

Go for 4x R9 270x

[lulutis2000]

i will check poolwarz thx!

[mattopia]

Go for 4x R9 270x

I second that.  The 270x are still pretty easy to find at not-ridiculously-inflated-prices.  I'm not running any myself but a good friend of mine has a 4x 270x rig pushing about 1.7Mh/sec easily - not too far off from what you'd get for 3x 7950, and at today's prices, probably at 1/2 to 2/3 of the cost. He's not even using risers.

[stepeato]

Great, ill look into that.  Thinking about going with the Gigabyte GA-990FXA-UD3.  Holds 6 GPU's, so if I do go R9 270 itll leave plenty of room for upgrades.  Also going to use one 750w PSU for the mobo and a card or two, and have an extra for the other cards.  Its far more cost effective than looking at the 12-1500w PSU's, there OUTRAGEOUS !

[showtimex]

That's probably a decent board though I don't have first hand experience with it. I have other Gigabyte boards, both intel and amd that work excellent for mining. It basically comes down to price and whats in stock. All of my boards are either Asrock, MSI or Gigabyte, all have been exceptional with few issues. For 5 slot AMD boards popular boards are 970 extreme 4 or the 970 gigabyte equivalent (there are also FM1/2 boards with 6 slot). Intel 6 slot MSI z77-gd45 or higher, gigabyte also makes several z77 6 slot boards.

750W with 5x 7850 (which btw can hash at over 400kh depending on the card) is OK but if you plan to expand get at least an 850W supply. for 270x I would recommend stepping up to a 1000W supply (can be found quite cheaply often with rebates) and make sure the powersupply has at least 8x pcie connectors, you will need up to 12 for 6x 270x. Quite frankly I think its better to go with the 270 rather than the X and save a few bucks and just OC them, they are exactly the same card with different clock speeds. Some of the 270 also only take/use one pcie power connector, this helps simplify installation.

Looking forward to try poolwarz out when they open my account!

[theomoplatapus]

7850 is slow as shit.  I've got one, it only does about 280kH/s.  Pointless.

You've got some work to do.  Mine does 386.

[stepeato]

Thats so much for the input fellas.  I plan on using two 750 watt power supplies.  If my research has led me in the right direction, I need to look for modular PSU's so I can power only the GPU's with the second.

Still thinking that going with the 7850's is going to be my best bet right now for the price per kh.  5x of these cards right now is only around $850 after tax and shipping and should hash between 1.5 - 1.7 MH/s.  The r9 270's (according to https://litecoin.info/Mining_hardware_comparison) should only hash between 420-470KH/s.

HOWEVER - While writing this post I am doing the most recent searches on these cards, and it looks like they can be found (r9 270's) for about $185 each after shipping.  So putting 5 of these which is comparable in price to the 7850's should hash about 2.2MH/s. 

Awesome, on my way to find two PSU's at the right price, and hopefully get some stuff ordered.  Ill post pictures when this is all setup and hashing, again, I cant thank you guys enough for the input, a single post by one of you can change my system for the better each time.

[Silverwolf_Ru]

7850 is slow as shit.  I've got one, it only does about 280kH/s.  Pointless.

Then you're doing something wrong mate. Mine pulls in around 414 Khashes/s It's cheap, it draws little power and still profitable to mine scrypt.