7/8 GPUs per Motherboard

[kslavik]

Just for your information : It is possible to run 2 motherboard with one PSU. If you can easily find cheap motherboard/gpu/ram that accept 4+ GPU (using pcie1x) then run 8+ GPU with one PSU.

I know that's not exactly what you aim for but it can be an alternative.

I wish there was a PSU with enough power to feed two motherboards with 8 GPU each. Usually the reverse is true: you would need 2 PSUs just to provide enough power to run 8 GPUs in one motherboard.

7950 card would take about 270-300W (mining scrypt), even if you have 5, it is already 1500W for GPUs only.
5970 card would take about 330w to run, so 4 of them connected to the one motherboard is 1320 for 4x5970 only.

Even if there was a PSU rated at 3000W, where would you plug it? You would need 30amp circuit to plug it in, and regular US circuits are only rated at 15amp, which is 1650W.

[superresistant]

Just for your information : It is possible to run 2 motherboard with one PSU. If you can easily find cheap motherboard/gpu/ram that accept 4+ GPU (using pcie1x) then run 8+ GPU with one PSU.

I know that's not exactly what you aim for but it can be an alternative.

I wish there was a PSU with enough power to feed two motherboards with 8 GPU each. Usually the reverse is true: you would need 2 PSUs just to provide enough power to run 8 GPUs in one motherboard.

7950 card would take about 270-300W (mining scrypt), even if you have 5, it is already 1500W for GPUs only.
5970 card would take about 330w to run, so 4 of them connected to the one motherboard is 1320 for 4x5970 only.

Even if there was a PSU rated at 3000W, where would you plug it? You would need 30amp circuit to plug it in, and regular US circuits are only rated at 15amp, which is 1650W.

I only use 6770 since they cost the equivalent of 66.5$ (new with shipping included) where I live.
I undervolt them to 0.8v (stock is 1.125v) so having 8 on a PSU is not a big deal.

But yeah, idk for 7950...

[kslavik]

I only use 6770 since they cost the equivalent of 66.5$ (new with shipping included) where I live.
I undervolt them to 0.8v (stock is 1.125v) so having 8 on a PSU is not a big deal.

But yeah, idk for 7950...

Because 7950 went down in price recently (I get them for $199), so they cost 3x as much as 6770 and at the same time they are 3.5 times more powerful than 6770 (hashing power). In addition I don't have to buy as many motherboards/cpus/memory/OS/hdd to run the same hashes. For 3250Khs (1 rig of 5 cards) I'm only getting one set of motherboard/cpu/memory/os/hdd.

8x6770 would produce about 1600Khs in one rig, right? So you would need 2 sets of hardware to run 3200Khs.


PSU would be the same because $/W of power would be about the same for 6770 and 7950 GPUs.

[InSpades]

Just for your information : It is possible to run 2 motherboard with one PSU. If you can easily find cheap motherboard/gpu/ram that accept 4+ GPU (using pcie1x) then run 8+ GPU with one PSU.

I know that's not exactly what you aim for but it can be an alternative.

I wish there was a PSU with enough power to feed two motherboards with 8 GPU each. Usually the reverse is true: you would need 2 PSUs just to provide enough power to run 8 GPUs in one motherboard.

7950 card would take about 270-300W (mining scrypt), even if you have 5, it is already 1500W for GPUs only.
5970 card would take about 330w to run, so 4 of them connected to the one motherboard is 1320 for 4x5970 only.

Even if there was a PSU rated at 3000W, where would you plug it? You would need 30amp circuit to plug it in, and regular US circuits are only rated at 15amp, which is 1650W.

Need to nudge you there - US circuits vary from state to state and what year the house was built in.  This is further broken down as per what is the wiring in the house used for (kitchen or washer/dryer units tend to have higher limits).  It is not uncommon for houses in the US to have a mix of 15 amp and 20 amp breakers.  My house is almost entirely wired up with 20 amp breakers (and I still overload them).

My 5 x 7950 rig fluctuates between 1575 and 1600 watts.  I have them load balanced between a 900w and a 850w.  

[kslavik]

Just for your information : It is possible to run 2 motherboard with one PSU. If you can easily find cheap motherboard/gpu/ram that accept 4+ GPU (using pcie1x) then run 8+ GPU with one PSU.

I know that's not exactly what you aim for but it can be an alternative.

I wish there was a PSU with enough power to feed two motherboards with 8 GPU each. Usually the reverse is true: you would need 2 PSUs just to provide enough power to run 8 GPUs in one motherboard.

7950 card would take about 270-300W (mining scrypt), even if you have 5, it is already 1500W for GPUs only.
5970 card would take about 330w to run, so 4 of them connected to the one motherboard is 1320 for 4x5970 only.

Even if there was a PSU rated at 3000W, where would you plug it? You would need 30amp circuit to plug it in, and regular US circuits are only rated at 15amp, which is 1650W.

Need to nudge you there - US circuits vary from state to state and what year the house was built in.  This is further broken down as per what is the wiring in the house used for (kitchen or washer/dryer units tend to have higher limits).  It is not uncommon for houses in the US to have a mix of 15 amp and 20 amp breakers.  My house is almost entirely wired up with 20 amp breakers (and I still overload them).

My 5 x 7950 rig fluctuates between 1575 and 1600 watts.  I have them load balanced between a 900w and a 850w.  

I just came back from the basement myself where I was resetting one of the circuit breakers because it couldn't not handle 1750w of power. I do have multiple circuits in the house too (it was built 2007, IL) ranging from 15 to 30amps, but all the circuits I can plug in my rigs, are 15 amps. I guess I could just replace them with 20 amps breakers but then I would have to check if wires are up to it.