Topic: Litecoin build for noobs: 3x 7950s (1.8 MH/s) in a $10 crate case - page 12. (Read 79077 times)

1. I'm not sure where this comes from, but it's really not an issue on any of my rigs so far (maybe if it gets hot enough, it will be).  Pull out an infrared heat gun and hit the caps with it, all mine are at under 30C.
2. Just because of getting enough molex cables from the PSU and the A1-B17 shorting issues.  Right now I have one rig with 4x 6950s and powered risers and it's like a jungle beneath the cards.

And yeah, if you want to power 4x 7950s you can, but I would just make another rig at that point.

All I know is that my 3x 7950 rig has mined for 6 months without issue.  I think it's less than ideal to pull (80w * 4 = 320w) from that motherboard, but that's just me.  If you want to put more cards on the board, just add powered extenders.  But be aware the the motherboards have high resale value anyway, and you need to buy progressively more expensive PSUs to power them.

Has anyone tried this built yet ? I ordered all the parts. I have to look around for a nice crate though, we don't have Home Depot here in The Netherlands.

When I start building I'll post some pics.

Be careful MKEGuy ! I'm sure there's a good reason why it's not viable for a long term solution. Can the motherboard keep powering 4 cards like that without, eventually, burning out somewhere ?

Taco we need your wisdom

I've found that for the 7 series (7970s myself), powered risers are completely not necessary.  I have two cards running 16x to 16x and two running 16x to 1x.  No jumper wire, no power, nothin.  Actually, technically 1 rig has 4 cards and 1 rig has 3 cards for now.  Ordering another 7970 very soon.  But funny enough the rig with 4 cards is the more stable rig for some reason.  I'm curious if that will change when I add another card to "balance" things out.  Though technically it shouldn't make a difference, experience has definitely taught me otherwise!

Nice little guide to get people pointed in the right direction.  A lot better then some of the advice I've seen floating around out there!!!!

Thanks for that noob built. I'm going to try it out ASAP.

Two questions :

1 How about airflow for the mobo ? I've read that there's parts on it that need some airflow to keep them from overheating.

2 Could you elaborate a bit on why using a powered riser is so much hassle ?


I did some math and all the parts for the machine , except for the GPU's,  cost €366.  If you add another GPU you would divide that cost by 4 instead of 3, €91 instead of €122 per GPU. I guess this is not a big enough number to risk frying a rig over though

And I also did not take into account how much more a more powerfull PSU costs. But you could use the same Mobo if you use 4 7950's, right ?

Hey men that is cool how many hashs do you do with all those gpus

Does the amount of 12v rails in the psu matter?

A good 850w psu can power 4 7950's on an energy efficient cpu setup. I've been running my corsair AX-850 golds like this for a while and have a seasonic gold doing the same.

Not a bad setup for the price. I built mine a year ago and each level was a add on and its all slides on and apart within a minute. Each motherboard tray pulls out to be serviced if it needs. Each level costs about $15-$20 to make. Some cheap thin aluminum angle with a few gussets makes for a decent structure that open exhausts well. You can see the top two levels I added an aluminum bar to screw the video cards into which was a nice addition to the setup. All the other cards are cable tied to the motherboards rails that hold the acrylic plastic.

Don't you think 850w is too small for 3 7950s? i have a 750w for my 2 7950 setup

Very nice guide taco!  I was just wondering, would it be better to use 16x to 1x cable risers instead of 16x to 16x?  You wouldn't need a mobo with all those 16x slots and I'm sure airflow would improve b/c 1x cables are obviously much narrower than 16x cables.

Box fan(s) moves far more CFM than almost any case. Good job, tacotime!

^I suggest cleaning the drivers (I used AMD cleanup utility after using catalyst uninstaller). If you are downgrading your opencl SDK/AMD APP, you may have to remove those specific files from your windows (or whatever) directory. The locations should be in the APP installation notes.


Although it could just be a bad reaper config.

grate idea taco thanks .But i still can get all my gpu's to there full potential ...I'm using 7950 maybe it is the driver from amd catalyst that is giving me problems and those not let me use the reaper.

Yes, modularity and cooling.  Also these are quicker to build, I can get about 10-20 units up and running in a day if I clone the HDDs.  The crates themselves only cost $2-3.

More Q's I'll post here

Q: All I need to do is just install windows and go from there?
A: Yes, you'll need a temp dvd drive or just install from a USB stick.  I just did this the other day, install windows, the driver + sdk, afterburner, and GUIminer-scrypt and go from there.  You may need to cut holes to put USB devices in, just use a cheap soldering iron.

Q: Would those components be the same if I were going to be running 10 units or would you personally use different equipment to maximize hash power.
What cards would make the units as productive as possible that are still available in large quantities?
A: Personally I would make them all like this.  You can fit a maximum of 7 cards in the rig, but I don't like doing that because that many cards makes a ton of heat right next to the board and will only save you about 70w (most modern mobos and cheap cpus only use ~70w).  Additionally, you need powered extenders for >3 cards and they are also a pain in the ass (molex cables everywhere, bad airflow).  The motherboards you buy have very high resale value so you can always just dump them in a year.

As far as scaling up, you can put two PSUs in a single crate and then put two rigs on either side.  You can then stack the units by cutting out the bottom on some more crates, putting these empty crates on top (the GPUs are above the top of the crate for me so you need to cut out the bottoms), then on top of these crates just install another 3x crates with 2x mobos and 2x PSUs.  
Like this:
### <-- etc
### <-- empty
### <-- 2x mobo, 6x cards, 2x psus
### <-- empty
### <-- 2x mobo, 6x cards, 2x psus
Because of the empty space, there's lots of air circulation and you can easily install 120mm or 200mm fans if you want to to help keep things cool.

Sapphire cards are available in very large quantities at the moment if you can't get MSI or don't want to spend more.

Cooling.

With ~$1350 worth of GPUs in there I'm not really sure why you wouldn't spring for the extra $40 for a proper case...

It really doesn't matter.  With this build the PSU is in another crate and you can tie up loose cables with cables ties.

You'll probably need at least one powered extenders.  I hate using them because it tends to make a clusterfuck with all the molex cable, but you're welcome to.