Power supplys .. HELP

[ajareselde]

long story short:

2x5850
1x5830
1x5770

power supplys are LC power 550w and LC power 650w.

650w powers the MBO and 1x 5850, and 550W is on other 5850 and 5830.

the problem is that after doing some numbers, i am afraid to plug in that last card (5770), im afraid psus will fail.

it says on them +12v rail 368w, on both of them.

for now its running without the 5770 and its super fine. do u think i can freely plug in the last card 5770?
if there is not enough power, will there be damage to cards or PSUs , or will it just shutdown,restart etc..

[1715537987]

1715537987

[crazyates]

2x 5850 = 2x 160W = 320W
1x 5830 = 130W
1x 5770 = 100W
Typical motherboard and system = 100W
Total draw: 650W.

I'd say connect the 5770 to the 650, and you'll have no issues. If you do have issues with power, they'll usually present themselves in the form of instability and crashes. Only in extreme cases where something is seriously wrong (like a hardware failure) will there be any serious consequences. You should be fine.

[goxed]

long story short:

2x5850
1x5830
1x5770

power supplys are LC power 550w and LC power 650w.

650w powers the MBO and 1x 5850, and 550W is on other 5850 and 5830.

the problem is that after doing some numbers, i am afraid to plug in that last card (5770), im afraid psus will fail.

it says on them +12v rail 368w, on both of them.

for now its running without the 5770 and its super fine. do u think i can freely plug in the last card 5770?
if there is not enough power, will there be damage to cards or PSUs , or will it just shutdown,restart etc..

Use a P3Killawatt and measure your actual power at the wall socket. Since the cards all use 12v rails, you will have guesstimate of your 12v draw.

[Gatorhex]

power supplys are LC power 550w and LC power 650w.

Not sure exactly what model of PSU you have but if they are similar to these PSUs
you will have no problems as they are high quality German build just make sure you
spread out the molex to PCI-e converters over many wires.


LC Power 550W http://www.lc-power.de/index.php?id=46&L=1
1x PCi 6pin + 1x PCI-e 6+2pin
2x 12V Rails 21A + 23A = 450W Total

LC Power 650W http://www.lc-power.de/index.php?id=197&L=1
1x PCi 6pin + 1x PCI-e 6+2pin
2x 12V Rails 25A + 27A = 550W Total

A good rule of thumb guide is this..
75w for each 6 Pin PCI-e Connector
150w for each 6+2 or 8 Pin PCI-e Connector
then double it.

[ajareselde]

to make things worse, my pci-e extenders dont have molex connectors, so the cards still draw from mbo a part of power.

im gonna give it a try later today, connecting it to 650w one.

cheers

[Meatball]

2x 5850 = 2x 160W = 320W
1x 5830 = 130W
1x 5770 = 100W
Typical motherboard and system = 100W
Total draw: 650W.

I'd say connect the 5770 to the 650, and you'll have no issues. If you do have issues with power, they'll usually present themselves in the form of instability and crashes. Only in extreme cases where something is seriously wrong (like a hardware failure) will there be any serious consequences. You should be fine.

You can't go off of just total wattage for PSU's.  You need to see how many rails there are and how much power if flowing down each of the rails.  A 650 W power supply might only be able to handle 325 on the video card power pin adapter cords.  Sometimes you can ease this by using molex adapters if the molex power line is a different rail, but it's different for every PSU.

That's why I never buy a PSU that isn't a single rail anymore.

[crazyates]

2x 5850 = 2x 160W = 320W
1x 5830 = 130W
1x 5770 = 100W
Typical motherboard and system = 100W
Total draw: 650W.

I'd say connect the 5770 to the 650, and you'll have no issues. If you do have issues with power, they'll usually present themselves in the form of instability and crashes. Only in extreme cases where something is seriously wrong (like a hardware failure) will there be any serious consequences. You should be fine.

You can't go off of just total wattage for PSU's.  You need to see how many rails there are and how much power if flowing down each of the rails.  A 650 W power supply might only be able to handle 325 on the video card power pin adapter cords.  Sometimes you can ease this by using molex adapters if the molex power line is a different rail, but it's different for every PSU.

That's why I never buy a PSU that isn't a single rail anymore.

While that is true, low power cards like 5830s and 5770s don't typically run into load balancing options. Even if that 650W can only output 325W, he's only got a 5850 on it, so there's plenty of room to add more.

We're not talking about 6990s or anything here. Then he'd be in big trouble.

[ajareselde]

ok, i tried both options, 650w  and 550w, but system wont power up with that last card connected.
i believe the problem is that i dont have pcie w/ molex adapter, so it uses some of wattage from mbo.

nevermind this. i am buying/making a new rig with 3x 5850/5870s, so ill add it there as 4th card.

Can someone recommend me a PSU that will have no problem running theese cards, so far my option is corsair tx 850. (single rail 12v) ?

[Meatball]

4 cards is really going to be pushing it with all but the biggest PSU's.  Figure 150-200 for each 5830 and 200-250 for each 5870.  I wouldn't go with anything less than 900-1000 watts.

That being said, I wouldn't spend _any_ money right now to build a GPU rig.  ASICs are right around the corner and going to make any GPU mining a waste of time and money.  Within a month of them coming out, GPU mining will be no better than CPU mining is right now.

[ajareselde]

4 cards is really going to be pushing it with all but the biggest PSU's.  Figure 150-200 for each 5830 and 200-250 for each 5870.  I wouldn't go with anything less than 900-1000 watts.

That being said, I wouldn't spend _any_ money right now to build a GPU rig.  ASICs are right around the corner and going to make any GPU mining a waste of time and money.  Within a month of them coming out, GPU mining will be no better than CPU mining is right now.

Its for LTC mining, i am counting on those ASICS

cheers

[superfastkyle]

I run 4 5850 bitcoin rigs on 650 watts power supplies (54 amp rail, corsair and rosewill) I don't know if that would work on ltc as ltc does use more power. I did have some stability issues when voltage dropped below 110v so I switched to 230v. It is right at the edge though.

if you want a recommendation though pc power and cooling 950 watt mk 2

[ajareselde]

I run 4 5850 bitcoin rigs on 650 watts power supplies (54 amp rail, corsair and rosewill) I don't know if that would work on ltc as ltc does use more power. I did have some stability issues when voltage dropped below 110v so I switched to 230v. It is right at the edge though.

if you want a recommendation though pc power and cooling 950 watt mk 2

it is so incredible that that works on a 650w psus. but on the other hand corsair is corsair.
the more i think about it seams i need 1kw to be sure.
cheers

[crazyates]

I ran a 5870, 5850, and 5830 on a 1kw PSU, and I never used more than 650W according to my kill-a-watt. This was with overclocks, no undervolting, and lower memory to 300.

[ajareselde]

I ran a 5870, 5850, and 5830 on a 1kw PSU, and I never used more than 650W according to my kill-a-watt. This was with overclocks, no undervolting, and lower memory to 300.

yes , but my 650w psu can deliver only 368w on 12 v Rails. that was the main problem.
i solved this by ordering  coolermaster 850w psu.

[ssateneth]

See, thats why I don't use multi-rail power supplies. Most will have 1 rail dedicated to -only- the CPU and mobo, and the others for molex and pci-e. You have an enormous amount of power locked to the mobo that you can't use, so its more like you have have a 250 w power supply.

I have a single 750 watt 80plus gold power supply powering 6 GPU's (all 5850 or 5870) which all run at 1 volt, except one 5870 @ 1.05v and a 5850 at an unknown voltage, likely about 1.15-1.2. I have never had any problems with the power supply turning off or failing and I've had it for about 6 months. My kill-a-watt shows something like 750-780 watts at the wall, which when factoring in ~90% efficiency, is still within tolerances. And yes, it's a single rail PSU.

You need to get better quality power supplies IMO.

[Meatball]

See, thats why I don't use multi-rail power supplies. Most will have 1 rail dedicated to -only- the CPU and mobo, and the others for molex and pci-e. You have an enormous amount of power locked to the mobo that you can't use, so its more like you have have a 250 w power supply.

I have a single 750 watt 80plus gold power supply powering 6 GPU's (all 5850 or 5870) which all run at 1 volt, except one 5870 @ 1.05v and a 5850 at an unknown voltage, likely about 1.15-1.2. I have never had any problems with the power supply turning off or failing and I've had it for about 6 months. My kill-a-watt shows something like 750-780 watts at the wall, which when factoring in ~90% efficiency, is still within tolerances. And yes, it's a single rail PSU.

You need to get better quality power supplies IMO.

Exactly.  Very often in the multi rail PSU's you see 20-30% of the total power being sent down the CPU/motherboard power rail/cords.  So say you're running a 900W power supply, 200-300 watts are on a rail just for CPU/Mobo and you're left with 600 watts for everything else.  If you're using a low power CPU, you can easily be 'losing' 100-200 watts of power capacity that's just sitting on that rail doing nothing.

Pay the extra for single rail PSU's.  It's usually not a huge price difference.  I looked on Newegg at 750W PSU's and the cheapest you can get is $60 (2 rails) and the cheapest single rail PSU is $70.   Well worth the $10 to not have to worry about what components are on what rails.  Not to mention that multiple rail PSU's almost always have cheaper/lower end internal components because they are built to handle less power down each rail/line where a single rail needs to have components strong enough to handle the full wattage down a single rail/line.

Imagine you had an air compressor that could put out 100 PSI of air pressure.  Would you want the model that has 4 outlets that could do 25 PSI each, or the one with a single outlet that does 100 PSI?  They are both '100 PSI' air compressors, but which do you think is built better?

[QuantumFoam]

The kill-a-watts work well for seeing the power draw, I used one to make sure my rig wasn't drawing too much for my corsair ax1200 psu. Despite ensuring this it still failed within 8 months with what was probably bad capacitors, so be careful, even the best regarded brands still fail. It's good to have a psu voltage monitor running while the gpus are mining so you can have an early warning of things starting to go wrong on the psu. I was lucky in that it failed in undervoltage, if it had been overvoltage I'd have fried gpus and a fried motherboard. Also, as stated, single rail is the way to go.

[dentldir]

Depending on your case situation, you can also do and Add2PSU and just add another power supply to drive 1 or 2 cards.  Its not an elegant solution, but it does work.  http://www.add2psu.com/.

Also, someone asked about mining LTC above.  Scrypt requires fast memory access so you can't drop your memory clocks like you can with BTC.  I'm not sure exactly how much power that saves but its a consideration.