bobbobobbo (OP)
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April 16, 2013, 06:31:20 AM |
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Qdentica
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April 16, 2013, 08:39:45 AM |
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I wouldn't try to go beyond 3 cards with 1050w, wouldn't be stable. 4 cards would mean pushing the PSU to a level of load which would only result in failure. Also, PSU's tend to get less efficient as they age.
3 cards it is!
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Tal1m0n
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April 16, 2013, 08:43:41 AM |
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i have free electricity and was hoping a bunch of people would sell their mining rigs but I guess interest in minning is higher than ever...
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bobbobobbo (OP)
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April 16, 2013, 09:06:59 AM |
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So 3 7950s on 1050w, what about 4 on a 1200w (gold rated)?
Or would that be pushing it...
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Railgun
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April 16, 2013, 09:31:46 AM |
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So 3 7950s on 1050w, what about 4 on a 1200w (gold rated)?
Or would that be pushing it...
3 cards. You may be able to get away with 4 cards if you under volt - get a electricity energy meter plug and check how much 3 cards consume when you under volt and make sure to take measurements when your box is at full load. Railgun.
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TeqnoHaxor
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April 16, 2013, 10:54:38 AM |
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7950s draw 200w, absolute maximum. If we're talking real power (Gold rated PSUs), then 1000w is more than enough for 3 cards. If you're using a budget or low power CPU (like Intel S and T processors) then you should be able to power 4 cards with a bit left over. I recommend the i5-3470T - at 35 watts you could easily run 4x 200w video cards.
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SamuelSG
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April 16, 2013, 12:38:07 PM |
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7950s draw 200w, absolute maximum. If we're talking real power (Gold rated PSUs), then 1000w is more than enough for 3 cards. If you're using a budget or low power CPU (like Intel S and T processors) then you should be able to power 4 cards with a bit left over. I recommend the i5-3470T - at 35 watts you could easily run 4x 200w video cards.
Have to call you on that, the 7950 under bitmining (BTC) load is around 175w on a reference card, and 186-188w on a weak factory OC to 900mhz (see charts here for evidence: http://www.tomshardware.com/reviews/radeon-hd-7950-review-benchmark,3207-9.html ). With significant overclocking, they can easily get close to the 7970's 250w TDP. While it is quite possible to stay under 200w, if you are going for the most hash's, it is far from being an absolute maximum. Also, I have heard in multiple places that LTC has a slightly higher power usage, but that could be hearsay, I have not borrowed my friends kill-a-watt to test my computer under BTC vs LTC mining. I will be borrowing it soon though (or relatively soon, as I live in rural Alaska, and he is almost 100 miles away) to test it. Edit: 1000 quality watts should be fine for 3 cards easy, I wasn't trying to contest that evaluation. Just trying to point out that it can be a significant load.
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vm1990
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April 16, 2013, 12:48:28 PM |
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simple 3 on 1050w 4 on 1200w
better to be safe than sorry and your PSUs will last longer if you dont max them out
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TeqnoHaxor
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April 19, 2013, 09:16:11 AM |
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Not one of the tests in the charts you link show power usage above 200w for the 7950. If you were overclocking to the point where you're using close to 250w per card - you've got way bigger problems than an undervolting power supply.
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Cryptorig
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April 19, 2013, 09:24:49 AM |
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I built 2 rigs yesterday with 3 hd7950s each (same ones as OP listed) on 860w seasonic platinum and they are running just fine overclocked and mining 1750KH/s LTC. I used sempron 45w CPUs.
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rovchris
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April 19, 2013, 09:37:29 AM |
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A rig with four 7970 that are overclocked by 100mhz will draw 1130 watts at the wall.
Each PCIE connector will draw between 10 and 12 amps at 12v.
Also the nearer to the limit of the PSU the less efficient it is - a cheap PSU will suck over an amp just for itself near full load.
Go big on the PSU
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Wabba
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May 12, 2013, 11:02:19 PM |
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Nice case lol.
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JoeRigs
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May 12, 2013, 11:22:45 PM Last edit: May 16, 2013, 07:29:56 AM by JoeRigs |
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Nice case lol Yeah they ain't pretty, but they're cheap, easy and keep the temps down. Just ordered four more. ($13 for two at Walmart) EDIT: The Walmart collapsible crates are a little smaller...damn!
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EdManet
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May 12, 2013, 11:24:07 PM |
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@JoeRigs How are you getting 560-570 out of a 7950?
Best i can do is ~525
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JoeRigs
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May 12, 2013, 11:41:54 PM |
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@JoeRigs How are you getting 560-570 out of a 7950? Best i can do is ~525 What cards are you using? Also, are you using Afterburner to tweak them? I used two gigabyte hd 7950s in my first rig and they both got 600 out of the box. Unfortunately, those cards are "voltage locked" and were harder to keep cool. So, I went with the Sapphire cards on the second rig...with some tweaking (shown in the Afterburner screenshot) I was able to get them up to where they are now. (I'm sure there is still room for improvement, but I'm OK with their current numbers.)
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moroz
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May 12, 2013, 11:50:38 PM |
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Well, 3x7970 @ 1100 clock pulling +-870 watts from the socket, no undervoltage, sempron CPU and no HDD. Using Corsair tx850 v2 PSU, so basically it's overloaded. This is one of the oldest 79** rigs, running for >12 months stable So, depends on PSU quality. I would probably burn 4x7950 on your 1050Wt PSU
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rovchris
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June 19, 2013, 10:54:03 AM |
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I bought a AX1200i as it has the on board data logging.
The AX1200i indicates that the load of 4 slightly overclocked Sapphire 7970 is over 1250 Watts
The biggest difference to how much load they pull is down to temp of the cards.
When they get to 80 degrees the load increase quite significantly. This is partly down to the fans running at max speed but also due to electrical resistance as the cards heat up.
A good quality Digital PSU will run above its stated max with no problems and it will still be 96% efficient
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BFL_Shill
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June 19, 2013, 11:34:18 AM |
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Wow that is a lot of cards. Good luck
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mooijman
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June 19, 2013, 12:14:08 PM |
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Now that's a cool case.. guess stacking a few riggs is the next thing right?
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