Topic: building a machine (Read 2386 times)

For a Radeon 7950, that's the best price I can also find among the different sites.

A variety of values seem to work OK. I get 640 kH/s from my MSI Frozr's at 14336 and 1100/1400, not too bad. ronaldinho_07, what card you getting 700 with?

If you're doing one pool, you only need one instance of cgminer running. Period. Doesn't matter if you're running 1 card, 3 cards, or 7 cards. The only real difference is if the cards themselves are disparate models and require different engine settings, memory settings, intensity settings (which, BTW, you can STILL get around by running one instance of CGminer and using comma commands.)

There are only a couple cases in which I can think of you might need multiple cgminers running on the same computer:
-You want each card to mine a different pool
-You want one card to mine scrypt, another to mine SHA256 (which is a variant of the "different pool" item)
-You want cards 2 and 3 to mine full out, and card 1 to mine desktop mode speed (essentially, intensity 9 instead of intensity 18 or 19)... and want to be able to just flat out stop card 1's mining when you REALLY need the power on a desktop app.

If you don't specifically tell cgminer to use device flags, like -d 1 (to use card 1)... it will use all devices available (1,2, and 3).

Bottom line though: To me, it makes no sense trying to split apart cards unless you have a REALLY REALLY good reason... it just adds complication. Remember the KISS principle.
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I'm still going to say 4GB RAM is VERY low for 3 7950s, and I'm still going to suggest 8GB RAM (meaning you will need a 64bit operating system... not that hard to get nowadays). I'm also going to say 750W for 3 7950s is asking for trouble, since a 7950's max TDP is 200W, your core component's power usage is about 110W in practice... meaning you are already at 710w. First hand experience with a Kill-a-watt and also seeing forums suggests that the cards actually exceed that TDP, and some forum claims say they can go as high as 250W... each. Getting an 850 is going to give you a system that has no expansion as a miner... which is ok for a first miner, but not good if you wanted to add a fourth card.

First hand experience with 7950's is that if you don't have them tuned right but use some of the suggestions off the litecoin mining hardware comparison, you get about 500-550... but many people say if you tune them right, you get 600+. I'm trying to tune my multiple Gigabyte 7950's rig with three of the same card, but purchased a month apart, and running into compatibility issues where they aren't stable above the 550 mark.

BTW, people have suggested you don't want to mix different manufacturer's of cards, nor do you mix different model numbers (eg 7950s and 7990's in same rig) or different generations (7950s and 6970's) in the same rig.

As to who to buy from... I've usually found tigerdirect to be overpriced more often than not compared to Newegg... and even Amazon sometime beats Newegg on prices at times... all while looking at the same exact item.

oh okay thank you for the commands i appreciate it
also the price you gave me for the 7950 is amazing !!! where do you get that price !??!? or where should i order it from , because with what i see the cards that you listed are easy over 350$$

you should buy 7950 or 7970
7950 ~ 219$ ($189.99 after $30.00 rebate card) ~ 640Khash
7970 ~ 325$ ( 305$ after rebate) ~ 740Khash
just use these commands : nothing = use all opencl card,if you had 4 card,without -d  = use all card
-d 0 -d 1 -d 2  = use card 1 2 3..that's all
find more here https://bitcointalksearch.org/topic/official-cgminer-mining-software-thread-for-linuxwinosxmipsarmr-pi-4110-28402

ok ive done more research and i kinda gave up on the system i just put together im going to be maybe getting another one or rebuilding another one i think that one was not good enough .. with the card i was getting, it was about 150 or 170 kh/s for the card i was getting

but the other thing is , where would i be able to get the commands for CGminer so i know which card to disable and like which card should be mining separately from the other , i wont be doing multiple pools i will be sticking to 1 pool but each GPU will be mining separately so i can get the most KH/s from them and the more LTC

and the other thing is i might change my power supply to a 850w cause i went through this http://images10.newegg.com/BizIntell/tool/psucalc/ and it recommended me a 710 so just to be safe ill go 750 or 825w for the power supply

also i would appreciate if you guys can help me out to pick a good card worth the price and what its doing , if you want to take a look at this and let me know
http://www.tigerdirect.ca/applications/SearchTools/item-details.asp?EdpNo=8511870&CatId=7387

or this card

http://www.canadacomputers.com/product_info.php?cPath=43_1200_557_558&item_id=056753

well did you see the system spec that i put up ?? thats the system i am getting ?!?! is that good or should i go better cards ??

and the question for me about the cgminer is how do i have each GPU doing different work ??!?! like GPU 1 mining separately then GPU 2 mining separately !??

or do i have to use GUIminer to be able to say " GPU 1 mine separately " " GPU 2 mine separately " ??!??

well did you see the system spec that i put up ?? thats the system i am getting ?!?! is that good or should i go better cards ??

and the question for me about the cgminer is how do i have each GPU doing different work ??!?! like GPU 1 mining separately then GPU 2 mining separately !??

or do i have to use GUIminer to be able to say " GPU 1 mine separately " " GPU 2 mine separately " ??!??

Pi's are really only good for mining if the device actually doing the mining is connected in over USB. I know I've seen setups of BFL Jalapenos and a Pi. I don't know if an FPGA can be hosted on a PI, but if a Jalapeno could be, shouldn't be any reason why an FPGA would have issues.

But the above, those are for SHA256 coins. Add in also USB Block Eruptors to that mix.

As to Scrypt coins (such as LTC and the many others that are looked upon with scorn by many on this board outside "Alternative Cryptocurrency"), you need to mine those with either a CPU or GPU. A Pi's CPU is VERY minimal, to the point that its probably not worthwhile. A Pi can't support the large amounts of RAM that a Scrypt system needs (4GB+, 8GB for anything really worthwhile), and does not have the PCIe bus or ports to host a PCIe GPU.

As to Scrypt-Jane style coins, the ones engineered to only be solved by CPU and not GPU... Pi can't do these either.

As was said above me, there are sites that say parts. I suggest you maybe look here on this site at TacoTime's crate build for a suggestion. As to video cards, do research in this forum you posted in, and also at the Litecoin Mining Hardware Comparison. Most of the time, the answer of which video card will be very similar regardless of SHA256 or Scrypt.

To answer your question as to if you need parts (without suggesting to you exact parts)... you DO need the following parts, and you need them for EACH rig. They're a full computer:

-Something to hold all your components, but which still provides an adequate air supply to the base of the cards (unless you are using a liquid cooling system). A typical computer case would seem the logical answer... but its often NOT the best answer in this particular case. Again, look at the crate build.

Core components:
-Motherboard
-CPU (and its cooler that usually comes with it)
-RAM
-Power Supply (adequately sized to your needs... don't skimp!)
-Storage (Some people say hard drive... some say USB drive. I personally do hard drives because they are also usable in other situations after I finish mining (Drobo, for instance), and to me a USB drive will take a little longer to boot from. Don't try to leap ahead by getting an SSD... that's a little overkill in this scenario.) PS: I've heard Linux mining systems won't run from USB... doesn't make sense to me, but thats what a few on the forum have said.

Hashing Power/accessories
-GPU - You have LOTS of choices... and the biggest hint is choose AMD, not Nvidia. Do your research very well before choosing. Keep in mind some cards have voltage locks on them, and may not be able to be as easily adjusted as others.
-Accessories - If at all possible, you want to try NOT to jam the cards up next to each other, so not plugging direct into the ports available on the motherboard. If you choose an alternative case like a milk/storage crate, you probably need to get riser cables (1-16, or 16-16)... and you probably also need to get something to attach the card to the crate (screws) and something to support the end of the card that's hovering in the middle of the case (I use a wooden paint stirrer stick.)

-Cooling System: Unless you're using a liquid cooling system to transfer the heat outside the box then dissipate a distance away (which is also a bit overkill), you'll be wanting fans. Not just fans to blow over your rigs to provide fresh air to the bottom of the cards and move hot air away from the top of the cards... but also something to ventilate the heat out of the top of the room to a location the heat is NOT... the rest of the house, a window, etc. Your room has a given amount of heat it can hold... if you don't move the heat out and let new air come in, the room will become warm, the cards will not be able to get rid of excess heat, and will cut off until the heat has dropped below a set level.

-You don't need an optical media drive. If you do, you really only need it for the initial setup. If you have your Windows install as an ISO, you can use Rufus and put it on an 8GB USB easy.
-If you're going for the crate setup... get zipties to hold things in place. You MIGHT also consider buying a momentary power switch, or you can set your computer to "On Power loss, restore power to ON."
-You're probably going to need a network switch, and network cables. (If you know how to make your own network cables, and have access to tools or are willing to put down money for tools... much better.)

For your whole setup, you'll probably want a single setup of monitor, keyboard, mouse too. You'll probably only use it now and then, but its useful to have it rather than moving your personal desktop one around.

In my case... for the fan nearest the computers, I didn't go super powerful... just enough to get a steady air supply moving. I'm mining in my unfinished fieldstone basement which also has a dehumidifier contributing to the heat, and needed to force the hot air upstairs to exhaust outdoors... so I got a powerful Vornado fan that can push a distance, for my exhaust fan. In the winter, though... I'll be sucking in enough cold air from the fieldstone walls that I probably won't need the exhaust fan, and if I do... its extra heat for the rest of my house.