Topic: How many 7950s can I run on this power supply? (Read 4256 times)
are you selling any 7950 ? if so let me know.. thnkx ..
mine x11, x13 coins you can use as many cards as you can plug to it then.
I love how we're giving answers to an OP who has not been on for 3 months 
For those newbies interested in mining a 7950 can be undervolted and would typically run just over 200W, so you could run 4 comfortably with scrypt. The more energy efficient coins are even better.
One thing to consider though, every 10C of ambient air temp will pull another 10% of power form the card. If you're running them in summer the resistance from heat and increased fan usage causes more power draw. Hence winter rocks!
For those newbies interested in mining a 7950 can be undervolted and would typically run just over 200W, so you could run 4 comfortably with scrypt. The more energy efficient coins are even better.
One thing to consider though, every 10C of ambient air temp will pull another 10% of power form the card. If you're running them in summer the resistance from heat and increased fan usage causes more power draw. Hence winter rocks!
3 cards for Scrypt, Scrypt-N, four cards of X11, X13
how many watts per card would I need to mine x11
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.
Nooooo ... you are wrong.
7950 hogs way more than 200w max.
3.
4 if you get under volt specific 7950's
4 if you get under volt specific 7950's
id say up to 5,
i have a corsair AX750 with the following setup:
gigbyte ud5h mobo
intel i7 3770k cpu
1x 5970 - both cores at 830mhz
1x 5870 - currently at 901mhz
1x 7970 - at 1125mhz
been running stable for the last ~month also have 5 hard drives in the machine always on. i am able to game and mine with the 5870 perfectly aswell. seems perfectly stable so far, in the process of looking for a watt meter in my silly excuse for a country
i have a corsair AX750 with the following setup:
gigbyte ud5h mobo
intel i7 3770k cpu
1x 5970 - both cores at 830mhz
1x 5870 - currently at 901mhz
1x 7970 - at 1125mhz
been running stable for the last ~month also have 5 hard drives in the machine always on. i am able to game and mine with the 5870 perfectly aswell. seems perfectly stable so far, in the process of looking for a watt meter in my silly excuse for a country
Now that's a cool case.. guess stacking a few riggs is the next thing right? 
Wow that is a lot of cards. Good luck
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
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
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
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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@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.)
@JoeRigs How are you getting 560-570 out of a 7950?
Best i can do is ~525
Best i can do is ~525
Quote
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!
Nice case lol.
I'm nowhere near an expert on all this (just started researching and building about a month ago), but I've got a 3-card 7950 rig on an 850 gold power supply. With the current Afterburner settings, it's running under 770 watts. (The processor should be about 65 watts of the total) I've attached pics for reference.
Side note: The reason I've got the "power limit %" on +9 is because it smooths out the GPU usage. For some reason, the Sapphire Radeon HD 7950s seem to jump all over the place at stock "0", and are stable at +9.
http://i1302.photobucket.com/albums/ag124/joephoto221/msi-shot_zpsdf6525ef.jpg
http://i1302.photobucket.com/albums/ag124/joephoto221/rig3_zps6b767996.jpg
http://i1302.photobucket.com/albums/ag124/joephoto221/2bdb8519-a227-40b7-ab0f-60aac7fd5165_zps4cbc7a15.jpg
Side note: The reason I've got the "power limit %" on +9 is because it smooths out the GPU usage. For some reason, the Sapphire Radeon HD 7950s seem to jump all over the place at stock "0", and are stable at +9.
http://i1302.photobucket.com/albums/ag124/joephoto221/msi-shot_zpsdf6525ef.jpg
http://i1302.photobucket.com/albums/ag124/joephoto221/rig3_zps6b767996.jpg
http://i1302.photobucket.com/albums/ag124/joephoto221/2bdb8519-a227-40b7-ab0f-60aac7fd5165_zps4cbc7a15.jpg
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
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
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.
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.
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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