Trouble with 7950's drawing way too much power.

[SybrCLocK]

Nice thread, so i`m joining....

Since i lost the train on ASIC's i decided to build a farm for LTC. Profit might not be big, considering that the cost /kW here is 0.172 cents, that means that almost half of my earnings will be spent on electricity.

But that is beside the point. I started out with 7 Motherboards (mostly ASRock Extreeme4). They have indeed 5 potential slots (3 PCIx16 and 2 PCx1).
Yesterday my Risers arrived (i bought unpowered ones because i decided to go with 4 Cards/Rig).

After setting up my rig (i used your custom chassis for inspiration)

i came across the usual issue (i have cards from a lot of brands):
-> cgminer has stopped responding
-> ATI driver crashes etc...

Ironed 90% of them out but one thing keeps popping into my head:
The PSUs. I was cheep and bought 1000W PSU's.

2 Rigs with respectively 4 cards run on 1000W PSUs
4x6970 (Sapphire)
4x6950 (Sapphire)

I should consider myself lucky from what i've read. Most people say not to put 80-90% Load on the PSU's as they will quickly die out. So now my dilemma:

Should i start selling off the current PSU's and buy smaller ones for dual setups or should i go ahead an get big ones (price wise that might be more expensive)

 

[ShrimpBrime]

What kind of benchmarks are you talking about? Unless its KH/s I will not have any.



These rigs are setup for mining only. They are running BAMT which is a custom Linux distro that is made only for mining. Besides initial setup the rigs are run headless.

I only have the monitors hooked up there in case they crash I can get them back up and running faster using a monitor vs SSH.


BAMT is really the only way to go with these mining rigs. I couldnt imagine having to deal with 3 windows installations mining 24/7.


My third rig is Windows based because its my main computer. Its an X58 and with three 7950's it only draws 900-950 W.


And thats a:

i7 965 EXE
EVGA FTW3 X58 (Did have the Rampage II but I Fed it up doing something stupid)
12GB DDR3 (6 x 2 GB)
Intel 520 240 GB SSD
2 Velociraptor 320 GB in RAID 0 (used to be boot drives until I got the SSD)
2 x Seagate 1.5 TB 7200 RPM
1200W Cooler Master Gold PSU
Thermaltake Level 10 Snow Edition
3 x 7950's

And all this only uses 900W







I have read of people having really good power savings with Gigabyte 7950's by flashing to the F43 (or something like that F something) BIOS.

Anyone know of a similar Sapphire BIOS? I looked on Tech Crunch and they dont specifically describe which BIOS are for which cards. I know Sapphire has tons of different 79xx models so maybe that is why.

That's a nice main rig! I got a buddy that has the same Cpu and a rampage board, just got himself a 680. Real stout system!

I hope this all "pays" out in the end. I thought about mining, but from all the talk about how unstable the stocks are, I never bothered.

 

[ShrimpBrime]

Nice thread, so i`m joining....

Since i lost the train on ASIC's i decided to build a farm for LTC. Profit might not be big, considering that the cost /kW here is 0.172 cents, that means that almost half of my earnings will be spent on electricity.

But that is beside the point. I started out with 7 Motherboards (mostly ASRock Extreeme4). They have indeed 5 potential slots (3 PCIx16 and 2 PCx1).
Yesterday my Risers arrived (i bought unpowered ones because i decided to go with 4 Cards/Rig).

After setting up my rig (i used your custom chassis for inspiration)

i came across the usual issue (i have cards from a lot of brands):
-> cgminer has stopped responding
-> ATI driver crashes etc...

Ironed 90% of them out but one thing keeps popping into my head:
The PSUs. I was cheep and bought 1000W PSU's.

2 Rigs with respectively 4 cards run on 1000W PSUs
4x6970 (Sapphire)
4x6950 (Sapphire)

I should consider myself lucky from what i've read. Most people say not to put 80-90% Load on the PSU's as they will quickly die out. So now my dilemma:

Should i start selling off the current PSU's and buy smaller ones for dual setups or should i go ahead an get big ones (price wise that might be more expensive)

Wow! very impressive.

 

[Knufire]

Little bit more complicated than that. Basically the number you see on the PSU isn't the max load you think it is.

Look on the label on the PSU, it should give another wattage just for 12V. This is a more realistic max load number as the CPU and GPU (which is the large majority of the power draw) all use 12V.

To clarify, you have two 6950s and two 6970s on each rig?

 

[SybrCLocK]

Little bit more complicated than that. Basically the number you see on the PSU isn't the max load you think it is.

Look on the label on the PSU, it should give another wattage just for 12V. This is a more realistic max load number as the CPU and GPU (which is the large majority of the power draw) all use 12V.

To clarify, you have two 6950s and two 6970s on each rig?

no... the only rigs with 4 cards of a 1000w PSU are:

4x6970 from Sapphire
4x6950 from Sapphire
Both run fine at stock speeds on pretty much no name 1000w PSU (True Power or something like that)

I need to measure the draw at the wall for my own peace of mine. But i`ll do that tomorrow when i`ll try to hook up 4x7950's to a 1000w PSU

But my initial question stands:

Sell off the 1000w PSU's and get 1500w ones or buy GOLD certified SeaSonic's (500w-600w) and dual PSU'em?

 

[Knufire]

You'll have to do the math as to which is cheaper. As long as both are quality PSU you shouldn't run into any issues. Be sure to factor in that you can get Gold/Platinum PSUs they cost more but are more efficient, so it saves you on the power bill.

 

[Bobnova]

A good PSU can run 80-90% load for it's warranty period, if not longer.

 

[SybrCLocK]

since single 1500W PSU`s are hugely expensive, i`m gonna go with 2x750 maybe

Looking at:
EVGA SuperNOVA NEX750G Gold 120-PG-0750-GR
Corsair Professional Series HX750 Gold CP-9020031
Sea Sonic X-750 SS-750KM

 

[Mjolnir]

since single 1500W PSU`s are hugely expensive, i`m gonna go with 2x750 maybe

Looking at:
EVGA SuperNOVA NEX750G Gold 120-PG-0750-GR
Corsair Professional Series HX750 Gold CP-9020031
Sea Sonic X-750 SS-750KM

Silverstone 1500

Not THAT expensive... >.>

 

[SybrCLocK]

god damn newegg!
i`m from Romania where **** is expensive: 409$ as opposed to the egg price off 300

@Mjolnir.. you play eve (caldari?)

 

[Mjolnir]

god damn newegg!
i`m from Romania where **** is expensive: 409$ as opposed to the egg price off 300

@Mjolnir.. you play eve (caldari?)

....No? LOL. Sorry

 

[LAC_STS]

I know this is an old thread but I wanted to update it.


What I ended up doing was finding a BIOS thats V was 1.09V. I run my 7950s at 1100/1550 24/7 at 1.09V and all is well.

This drop in V was a huge savings in wattage. My 5 card rigs went from 1600-1700W to 1100W. The cards are 24/7 stable. My BAMT rigs have been running for almost two months non stop at 99% load on all the GPUs.

I dont know why Sapphire sets these cards to run at such a high V. 1.25V is stupid if the cards will run at 1.09V.

Heres a snip. The changes in temp are from me changing how much the door in the rig room is open. Just an inch or two more open or more closed has an almost 5 degree diff in temp on the cards. And those temps are 3 rigs in one small room. Its hot in there.