Litecoin build for noobs: 3x 7950s (1.8 MH/s) in a $10 crate case

[coinedabit]

So.. what are the main things to watch out for when putting 4x7950 cards in the rig?
Things like 4 cards needs a larger psu if overclocking?
or extra fan needed for cooling etc.
Any help appreciated. just trying to work a way of putting 4 in one machine so is cheaper to buy overall. i intend to have 3 @ 2400 ghs.
cheers

[1714788796]

1714788796

[1714788796]

1714788796

[rbbrdckybk]

With 4 cards, you should probably think about using at least one powered riser, or something like this:

http://www.evga.com/Products/Product.aspx?pn=100-MB-PB01-BR

Each card will draw 75w from the motherboard, and some aren't designed to be able to deliver enough to power 4+ GPUs.

So.. what are the main things to watch out for when putting 4x7950 cards in the rig?
Things like 4 cards needs a larger psu if overclocking?
or extra fan needed for cooling etc.
Any help appreciated. just trying to work a way of putting 4 in one machine so is cheaper to buy overall. i intend to have 3 @ 2400 ghs.
cheers

[BitRock]

I actually have another setup I'm working on now which uses dual XFX 850 pro's to power 6 7950's on an MSI Z77-g41 board with an I5 2500k

As you know, there are only 4 PCI-E slots on MSI Z77-g41 board. So I am wondering how do you put 6 7950's on this motherboard.

[akipfer]

I have two 7950s and I am able to get between 550-600 kH/s using GuiMiner-scrypt's default 7950 settings. Usually, it is around 560 kH/s. Once it was running stable at 605 kH/s but that was the first time I used it and haven't seen that consistently since, even though I think I am using the same settings.

You have to imagine that many of these stories about higher than normal hash rates are just that - that is how message boards are, there are always those Keyboard commandos that can do the most amazing feats. 

hi dear friend, i bouth 2 xfx 7950
on CGMINER i get  around 500 kh/s with both GPUz, kinda 150kh/s GPU[0] and 350kh/s GPU[1]
even on Guiminer, afaik one 7950 should do 500 - 550 kh/s, EACH gpu, i'm i right?

why when i use 2 GPUs the kh/s drops like an falling airplane


pls, need help

also, when mining, some artifacts show up on the deskop, fuckin werdo

[txmasut]

My rig is a little different but I wanted to see if anyone else was having this happen.  I currently have five 7950's on risers and every
time I start Cgminer at least one GPU is deactivated and I have to enable it in the settings.  Does anyone know how to get them to be
activated all the time?  It is very annoying to have an auto-restart while I'm gone and find that only 3 of the 5 GPU's were active.

[akipfer]

can some one help me please... read two reply above(look for my nickName akipfer)

[akipfer]

My rig is a little different but I wanted to see if anyone else was having this happen.  I currently have five 7950's on risers and every
time I start Cgminer at least one GPU is deactivated and I have to enable it in the settings.  Does anyone know how to get them to be
activated all the time?  It is very annoying to have an auto-restart while I'm gone and find that only 3 of the 5 GPU's were active.

tell me your .bat (cmd live cgminer)

i will try on my own 2 cards, i can't pass 420mh/s each

[txmasut]

My rig is a little different but I wanted to see if anyone else was having this happen.  I currently have five 7950's on risers and every
time I start Cgminer at least one GPU is deactivated and I have to enable it in the settings.  Does anyone know how to get them to be
activated all the time?  It is very annoying to have an auto-restart while I'm gone and find that only 3 of the 5 GPU's were active.

tell me your .bat (cmd live cgminer)

i will try on my own 2 cards, i can't pass 420mh/s each

:loop
C:\Users\loans_000\Desktop\cgminer\cgminer.exe -c C:\Users\loans_000\Desktop\cgminer\cgminer2.conf
timeout /T 10
goto loop

color 70
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
cgminer --scrypt -o stratum+tcp://eu.wemineltc.com:3333 -u USERNAME -p PASSWORD -o stratum+tcp://coinotron.com:3334 -u USERNAME -p PASSWORD --shaders 1792 --intensity 18 --worksize 256 -v 1 --lookup-gap 2 --gpu-threads 1 --thread-concurrency 24000 --gpu-engine 1100 --gpu-memclock 1575 --gpu-vddc 1.119

[akipfer]

My rig is a little different but I wanted to see if anyone else was having this happen.  I currently have five 7950's on risers and every
time I start Cgminer at least one GPU is deactivated and I have to enable it in the settings.  Does anyone know how to get them to be
activated all the time?  It is very annoying to have an auto-restart while I'm gone and find that only 3 of the 5 GPU's were active.

tell me your .bat (cmd live cgminer)

i will try on my own 2 cards, i can't pass 420mh/s each

:loop
C:\Users\loans_000\Desktop\cgminer\cgminer.exe -c C:\Users\loans_000\Desktop\cgminer\cgminer2.conf
timeout /T 10
goto loop

color 70
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
cgminer --scrypt -o stratum+tcp://eu.wemineltc.com:3333 -u USERNAME -p PASSWORD -o stratum+tcp://coinotron.com:3334 -u USERNAME -p PASSWORD --shaders 1792 --intensity 18 --worksize 256 -v 1 --lookup-gap 2 --gpu-threads 1 --thread-concurrency 24000 --gpu-engine 1100 --gpu-memclock 1575 --gpu-vddc 1.119

GPU engine and gpu-memclock is for OC right? since i don't want OC, i just dont use this 2 cmds right?

edit -> Where i put this? in .BAT right? cause of :loop i think is .bat

[meyerbtc]

Could I use 3 x HD7950 with the GA-H77-DS3H?

It has:

• 1x PCI-E 3.0 x16 @ x16
• 1x PCI-E 2.0 x16 @ x4
• 2 x PCI-E 2.0 x1

From what I read you can use a HD7950 on a PCI-E x1 without any disadvantage. But maybe I'm wrong.

[akipfer]

U can, but be aware that using PCIe x1 will, for sure overheat the flat cable, so 100% alert and careful to avoud damages okay?

i'm not sure how do make it not to overheat..maybe ask over here to see if some one has it.

[chopsbit]

Has anyone on this thread got a Gigabyte 7950 that's voltage locked? Most people seem to be having a lot of success with the MSI 7950, but the one I've got is voltage locked

The best performance I can get is 550 KH/s using these params:

--thread-concurrency 20000 --shaders 1792 --lookup-gap 2 -I 20 -g 1 -w 256 --gpu-engine 1100 --gpu-memclock 1575 --gpu-powertune 0  --auto-fan


I've tried setting --gpu-powertune however no difference in performance, and setting --thread-concurrency to anything higher than 20000 causes CGMiner to not even load!

[503guy]

Has anyone on this thread got a Gigabyte 7950 that's voltage locked? Most people seem to be having a lot of success with the MSI 7950, but the one I've got is voltage locked

The best performance I can get is 550 KH/s using these params:

--thread-concurrency 20000 --shaders 1792 --lookup-gap 2 -I 20 -g 1 -w 256 --gpu-engine 1100 --gpu-memclock 1575 --gpu-powertune 0  --auto-fan


I've tried setting --gpu-powertune however no difference in performance, and setting --thread-concurrency to anything higher than 20000 causes CGMiner to not even load!

set your TC to 22272, take shaders out (don't need it), remove lookup gap, Intensity 19, gpu engine 1100, memclock 1400, remove powertune.  let me know what you get.

[takagari]

Would this be the best bet mobo for running 4 eventually?

http://www.newegg.ca/Product/Product.aspx?Item=N82E16813130653

I'd probably start with two.
Also if you'd like I could suggest a mini SDD hDD, less heat and power consumption?

What CPU should I put in the above mobo if it's a good choice?

Tanks

[2Kool4Skewl]

U can, but be aware that using PCIe x1 will, for sure overheat the flat cable, so 100% alert and careful to avoud damages okay?

i'm not sure how do make it not to overheat..maybe ask over here to see if some one has it.

I don't believe this is true.  All the extender cables PCIe x1-x16 have the same 12v power wires.  The only difference is that they have less data wires.  You'll draw the same power through a pcie x1 extender as you will through a pcie x16 extender.

If you're concerned about drawing too much power through the mobo just use an extender with a molex soldered to the 12v power lines.

One extender won't heat up more than another unless you're comparing an extender with a molex power plug too an extender without a molex power plug.  The extender without the molex plug will get hotter as it is drawing more power from the motherboard.

[chopsbit]

Has anyone on this thread got a Gigabyte 7950 that's voltage locked? Most people seem to be having a lot of success with the MSI 7950, but the one I've got is voltage locked

The best performance I can get is 550 KH/s using these params:

--thread-concurrency 20000 --shaders 1792 --lookup-gap 2 -I 20 -g 1 -w 256 --gpu-engine 1100 --gpu-memclock 1575 --gpu-powertune 0  --auto-fan


I've tried setting --gpu-powertune however no difference in performance, and setting --thread-concurrency to anything higher than 20000 causes CGMiner to not even load!

set your TC to 22272, take shaders out (don't need it), remove lookup gap, Intensity 19, gpu engine 1100, memclock 1400, remove powertune.  let me know what you get.

Gave that a try and had same error. I had a few more experiments and I ended up with this which is ticking over at an average of 636 KH/s:

--temp-target 70 --thread-concurrency 20000 --shaders 1792 --lookup-gap 2 -I 20 -g 1 -w 256 --gpu-engine 1050 --gpu-memclock 1450 --gpu-powertune 10


The one thing that helped me for some reason was to make sure I removed the --gpu-autofan option, this really seemed to help with my temperatures and keeping things ticking along at 57C - 61C. For reference, this is the card I'm using: http://www.dabs.com/products/gigabyte-ati-radeon-7950-hd-800mhz-3gb-pci-e-hdmi-windforce-3x-oc-7XN5.html?q=7950&src=16

[Vigil]

One of my cards keeps crashing. I have all the default settings applied and after a bit of runtime cgminer scrypt within GuiMiner stops working for one of my cards. I recently started seeing extremely high temps - 100C - I heard my fan going insane and I shut it down. There is plenty of ventilation, I have good power supplies running these cards. I know know this isn't a lot of information but would a bad card cause cgminer to crash or is there possibly something else going on?

[AmDD]

One of my cards keeps crashing. I have all the default settings applied and after a bit of runtime cgminer scrypt within GuiMiner stops working for one of my cards. I recently started seeing extremely high temps - 100C - I heard my fan going insane and I shut it down. There is plenty of ventilation, I have good power supplies running these cards. I know know this isn't a lot of information but would a bad card cause cgminer to crash or is there possibly something else going on?

what brand card is it? I had some PowerColor HD7950s that would reach some pretty crazy high temps. I have since gotten rid of them.

[Vigil]

One of my cards keeps crashing. I have all the default settings applied and after a bit of runtime cgminer scrypt within GuiMiner stops working for one of my cards. I recently started seeing extremely high temps - 100C - I heard my fan going insane and I shut it down. There is plenty of ventilation, I have good power supplies running these cards. I know know this isn't a lot of information but would a bad card cause cgminer to crash or is there possibly something else going on?

what brand card is it? I had some PowerColor HD7950s that would reach some pretty crazy high temps. I have since gotten rid of them.

They are Sapphires - the OC. I have two reference Sapphires I have not hooked up yet so maybe I will replace one and see what happens.

If I put one card in it gets so hot I can't touch it. If I put two cards in only one of them overheats. It makes no sense.

Oh, and I didn't have any problem when I first put two cards in after using an additional psu. It does matter which of the three cards I've used - they will overheat.

[bdub]

I see several people reporting incredible performance efficiencies in this thread and I want to know your secret.  I'm interested in what settings you are running.

Here's what I have:
- ASRock Extreme 4
- Sempron 145
- 4GB RAM
- USB Flash Drive
- PC Power and Cooling Silencer MKIII 1200 (Platinum rated)
- 4x Sapphire 2L 7950s

I flashed my cards to undervolt them to 1.09V (using Sapphire Twin-X bios).  Stock bios was 1.25V unlocked, but needed to flash for Linux.
I run BAMT with CGMiner.
I currently run them at 1050 core/1500 memclock (.7 relation seems best) => ~625kh/s each and my kill-a-watt reads around 950w

Estimating high, lets say everything except the GPUs pulls 100 watts (i.e. CPU/RAM/USB/Mobo), that means each of my cards is pulling roughly 193.5w (@92% PSU efficiency).  Using the same estimation of 100w (CPU/RAM/HDD/Mobo), I see people with setups pulling 155-175w (a generous estimation of 90% PSU efficiency) per card and getting better hash rates on top of that.

If someone is able to help me increase my efficiency to these numbers, I will gladly send some LTC your way for your help!