A new challenger appeared !

[Zemou]

Hello all !

I'm Zemou from France. Starting mining alt currencies. I've been lurking this forum for a while and decided to do my first post

Here a picture of my mining rig with 3x HD7950 and 1100 watts PSU and made of wood (around 4 hours of wood work...) :
http://img11.hostingpics.net/pics/984067photo.jpg
EDIT : The picture is from the top of the mining rig. Card are in vertical configuration. I'm planning to add 3x 140mm cooling fan at the bottom of the case to bring the fresh air.

Each card is currently mining Litecoin at 640 Mhash/sec with the following O/C : 1070 Mhz / 1650 Mhz @ 1,10, all fans at 100% and each card is around 70°C.

As you notice on picture, there is also a HD6950 waiting to mine.
If I plug it, Windows doesn't start at all. In fact, Windows will don't boot at all if I use more than 3 graphic cards (whatever combination between HD6950 and HD7950).
Does anybody have an idea about what happens ?

Another question, does my HD7950 configuration/OC looks good for 24/7 mining ?

Thanks !

[pontiacg5]

I'd bet the 4th card won't work because you are putting too much of a load on the PCI-e bus voltage. Are you using powered riser cards? It doesn't really look like it. I'd try using one or two and see if windows boots then.

[balanghai]

Have you calculated your electricity costs over profit? I wonder how much electricity costs per Kwh there in France. Anyway Bonjour Mon Ami. 

[Zemou]

Indeed, I don't use powered risers.
I've to find where I can buy some of them...

For electricity, I pay 0,08 € / Kwatt hour. Following my calculation, it should be profitable (Something like 50% of revenue for electricity and 50% in my pocket).
But I've already ordered a kill o watt to be check my estimated electricity consumption...

[pontiacg5]

You might be able to modify the ones you have, or at least that one extra. I believe I've seen a thread on the subject around here before. If you are good with soldering I'd give it a try.

[marcovaldo]

Good luck mining.

[Zemou]

You might be able to modify the ones you have, or at least that one extra. I believe I've seen a thread on the subject around here before. If you are good with soldering I'd give it a try.

Yes, I've seen this topic about homemade powered risers. I will make a try.

BTW, other people told me I need a dummy plug on this card. What do you think about that ?
(I'm using Windows 7 with Catalyst 12.

[b!z]

hi, nice rig! looks very good, i'm jealous.

[Zemou]

hi, nice rig! looks very good, i'm jealous.

Thanks
Made with 10 € of wood, some glue and nails.
I'm already thinking of making a new one as this one haven't enough space for the PSU.

[pontiacg5]

You might be able to modify the ones you have, or at least that one extra. I believe I've seen a thread on the subject around here before. If you are good with soldering I'd give it a try.

Yes, I've seen this topic about homemade powered risers. I will make a try.

BTW, other people told me I need a dummy plug on this card. What do you think about that ?
(I'm using Windows 7 with Catalyst 12.

A dummy plug won't keep windows from starting, it'll just keep the card from showing up in CGminer when you go to use it. I used single 75ohm (I think) resistor just shoved into the DVI plug on the card for a time.

[Zemou]

I think I've found my final O/C but I'm a bit surprised with my values :
1050 cpu / 1500 memclock @ 1.000
Sucking about 350 Watts at wall plug (I've got a 1100W PSU with silver certification).
I was thinking about adding a fourth HD7950 but I will already reach the limit with these three...

Is it a normal watt value for a HD7950 ?

Should I underclock to be able to put the fourth card ?

[balanghai]

I think I've found my final O/C but I'm a bit surprised with my values :
1050 cpu / 1500 memclock @ 1.000
Sucking about 350 Watts at wall plug (I've got a 1100W PSU with silver certification).
I was thinking about adding a fourth HD7950 but I will already reach the limit with these three...

Is it a normal watt value for a HD7950 ?

Should I underclock to be able to put the fourth card ?

Yeah underclocking would be better in the long run because additional rig would make you lose on electricity due to extra consumption (Hard Drive, Ram, Processor, Board, etc.). Also you could crank down your mining software settings to minimize consumption.

[Zemou]

I'll watch for underclock/undervolt...

Another question :
One of my HD7950 keep crashing everytime I start mining with it (ATI display driver crashes and Windows recover it). I was overclocking it...
Now even at stock frenquency, it still crashes...
Nevertheless, it seems to work good while the computer is idle. I also can plug the HDMI into it and the image is good on my screen.

Any suggestion about this ?

[monbux]

Wood?  Is that dangerous?  Flammable?

[Zemou]

Wood?  Is that dangerous?  Flammable?

Ahah! I will put some special paint against fire on it

By the way I solved all my issues.

Is it a good performance to hash at 1900 MHs/s for a total consumption of 750 Watts ?

[iANDROID]

Nice!

C'est du beau travail 

[lws]

Wood are bad thermal conductor. And it is flamable.. It beter to use aluminium. Its cheap and easy to cut.

[Zemou]

I know a wood frame can be a bit risky but will not burn with 70°C... By the way, the system is in the basement of my place which is fully made of stone :p

BTW, I solved all my problems (stability, windows doing shit, card not recognized) by throwing away GUIminer and using CGminer instead.
Moreover, I have some room to undervolt a bit more ! I decided to stay at 1050 / 1500 mhz as it provides satisfying hash rates (around 630 Kh/s per card for a good).

Right now, two cards are "optimized"
@ 1.024 V
@ 1.012 V
The last one is still "in progress" but I will don't reach so good voltage as the ASIC quality shown in GPU-Z is very bad (66%).

I already disconnected all useless stuff on the motherboard but I still have to underclock/undervolt the CPU and the RAM (Is someone has a good guide to do this ?)

More pictures soon, I've added a space for PSU on my wooden case and managed all cables to make it "portable".

[torrentheaven]

Is it a good performance to hash at 1900 MHs/s for a total consumption of 750 Watts ?

Yes, I hashed with 5850 somewere 350MH and 400W total. But the difficulty I stopped was 4M 

[stylesuxx]

Is it a good performance to hash at 1900 MHs/s for a total consumption of 750 Watts ?

Hmm I don't think so. You can get 1900MH/s with ~ 6 Block Erupters each consuming 2.5W totaling in 15W.
This would be the same hashing power at 1/50 of the energy cost.