Author Topic: Sapphire Radeon 7950 Questions - Different Models  (Read 1626 times)

Offline CryJim

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Sapphire Radeon 7950 Questions - Different Models
« on: February 03, 2014, 05:17:56 AM »
I have a Litecoin / scrypt mining rig. It has 4 Sapphire HD 7950's. Three are model 11196-19-20G. The other is a 21196-00-20G. The 11196's work a lot better. Faster speed, much cooler.

Here is a sshot of my current cgminer. The 21196 is GPU #0.



You can literally feel the difference in heat coming off the 21196 card. Seems even hotter physically in comparison to the 11196's than what the sshot above indicates.

Is this difference normal? I thought that all 7950's should be almost identical in speed / heat. Should I try and adjust the setting for the 21196 differently than the 11196's? I had originally set more aggressive settings (Intensity setting, .etc.). Which worked fine for the 11196's, but caused the 21196 to die. So I just scaled back the settings for all the GPU's.

Also, it seems like I am getting a high percentage of Rejects for all four cards.

Any ideas or suggestions would be most appreciated.

Offline Trololo2060

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Re: Sapphire Radeon 7950 Questions - Different Models
« Reply #1 on: February 03, 2014, 05:50:04 AM »
Check the cooling of you rig

May be it just local overheating for the first card

About rejects - try another pool and check

Offline CryJim

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Re: Sapphire Radeon 7950 Questions - Different Models
« Reply #2 on: February 03, 2014, 06:47:22 AM »
Trololo2060: Thanks for your response. Sorry to be such a Noob, but how would I check the cooling on my rig? Specifically, how would I check the one GPU card in particular, separate from the others? Will try a different pool per your suggestion and see how the reject ratio compares. Current pool is a multipool. Will try a Litecoin only pool and see what happens. Any pool in particular you'd recommend?

Offline pguerrerox

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Re: Sapphire Radeon 7950 Questions - Different Models
« Reply #3 on: February 03, 2014, 12:33:15 PM »
Trololo2060: Thanks for your response. Sorry to be such a Noob, but how would I check the cooling on my rig? Specifically, how would I check the one GPU card in particular, separate from the others? Will try a different pool per your suggestion and see how the reject ratio compares. Current pool is a multipool. Will try a Litecoin only pool and see what happens. Any pool in particular you'd recommend?

are you using risers?
is the RIG build in a normal case or open air?

your rejects are not that bad, its around 2%.....

those hash values are a bit slow for 7950's if you want to get them optimized, check the link in my signature.
goodluck.

Offline Shellshock

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Re: Sapphire Radeon 7950 Questions - Different Models
« Reply #4 on: February 03, 2014, 12:44:08 PM »
Trololo2060: Thanks for your response. Sorry to be such a Noob, but how would I check the cooling on my rig? Specifically, how would I check the one GPU card in particular, separate from the others? Will try a different pool per your suggestion and see how the reject ratio compares. Current pool is a multipool. Will try a Litecoin only pool and see what happens. Any pool in particular you'd recommend?

Do you see the screencap you provided? Next to where it says:

GPU 0: 82.0 C
GPU 1: 71.0 C
GPU 2: 75.0 C
GPU 3: 69.0 C

Those are the temps of your cards. Your temps are OK, but could be lower. Sometimes if a card gets hot it becomes less efficient. I don't know how your set up is, but try to introduce more airflow, or decrease ambient temperatures if possible. I am not sure if this is what you were asking, but I hoped it helped.

Also, I would not mine litecoin at the moment. Mine doge or another alternative cryptocurrency, and exchange to litecoin. You will get more Litecoin that way.

Lastly, it looks like your cards are not overclocked. Or are very stock-ish OC. Pguerrerox can help you tweak the settings. If you are afraid for the cards temps, I would recommend CGwatcher. It changes the intensity and temps in co-relation dynamically to always optimize intensity vs temperature.

Hope this helps
Bitch you not a Hobbit, right?

Offline Viktor.E

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Re: Sapphire Radeon 7950 Questions - Different Models
« Reply #5 on: February 03, 2014, 01:07:05 PM »
Hi,

I'm using a Sapphire hd7950, which is a 11196-19-20G
It give me 680KH/s for a temp at about 70°C and fan below 60% (56% for the moment)

What could you try ?
1/ First lower power consumtion and undervolt.
Use atiflash to save a backup of the bios of ALL you cards. Don't do anything with bios if you have not backup.
Then use vbe7 to reduce voltage from 1.25 to 1.081 (try 1.113 if too low, depends on the quality of your PSU. I'm using 1.125 now) and TDP from 233W to 200W or less (my hashrate drop below 190W).
try this modified bios on all your cards, including the N°4

2/ try this values: TC 24000, shaders 1792, gap 2, thread 1, temp target 72, vddc 1.125, worksize 256
then try to overclock a bit. I'm using gpu-engine 1100 and memory 1500. Since I've undervolted, temp doesn't go above 70. And since I'm limiting power, it doesn't increase too much to.

3/ increase intensity step by step from 13 to 19 or 20 (stop if hashrate drop)

4/ last, when all is working well, use an optimized scrypt kernel (from 'lantis' or another guy). It give me 30kh/s more


Did I help you ? Consider making me happy:
FTC: 6pm6d1ohHAWUBhWDBbGbapT1cwZTM4d1wT
BTC: 1M3AXAo8MoKeoEo8fvFT711EyTj5UwyApu
LTC: LdNgoQdj5Ho9Tvpryzbi1WvMCHCJFfYPPu
(sorry if bad english, I'm french)

Offline CryJim

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Re: Sapphire Radeon 7950 Questions - Different Models
« Reply #6 on: February 03, 2014, 11:52:36 PM »
pguerrerox:

Quote
are you using risers?

is the RIG build in a normal case or open air?

your rejects are not that bad, its around 2%.....

those hash values are a bit slow for 7950's if you want to get them optimized, check the link in my signature.

1) Yes, powered risers.
2) Open air crate

Photo of rig setup. The 21196-00-20G card is the one at the bottom of the picture, slightly separated from the rest.



3) Current reject rate is around 4%. What is considered good / acceptable?
4) What would you charge to optimize for me via TeamViewer?


Shellshock:

Quote
Those are the temps of your cards. Your temps are OK, but could be lower.

I would recommend CGwatcher.

1) My main question / concern is why the one 21196-00-20G is running so much hotter (82C) than the three 11196-19-20G 's (69C to 75C). Is this normal?

2) Thanks. I've downloaded CGWatcher and will check it out.


Viktor.E

Thanks for the great suggestions!

Offline pguerrerox

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Re: Sapphire Radeon 7950 Questions - Different Models
« Reply #7 on: February 04, 2014, 12:10:16 AM »
the GPU black and red is a sapphire 7950 reference, really good card...  it is running hotter because it only have one fan and its tune to run at the same % as the other with two fans....  increase the fan speed and get a fan to push fresh air from the top off all the cards.


Offline j4r3k

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Re: Sapphire Radeon 7950 Questions - Different Models
« Reply #8 on: February 04, 2014, 12:18:13 AM »
I would span the cards more. Sucking hot air from the rig is more effective than blowing cold on it.

Offline Shellshock

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Re: Sapphire Radeon 7950 Questions - Different Models
« Reply #9 on: February 04, 2014, 12:22:33 AM »
pguerrerox:

Quote
are you using risers?

is the RIG build in a normal case or open air?

your rejects are not that bad, its around 2%.....

those hash values are a bit slow for 7950's if you want to get them optimized, check the link in my signature.

1) Yes, powered risers.
2) Open air crate

Photo of rig setup. The 21196-00-20G card is the one at the bottom of the picture, slightly separated from the rest.



3) Current reject rate is around 4%. What is considered good / acceptable?
4) What would you charge to optimize for me via TeamViewer?


Shellshock:

Quote
Those are the temps of your cards. Your temps are OK, but could be lower.

I would recommend CGwatcher.

1) My main question / concern is why the one 21196-00-20G is running so much hotter (82C) than the three 11196-19-20G 's (69C to 75C). Is this normal?

2) Thanks. I've downloaded CGWatcher and will check it out.


Viktor.E

Thanks for the great suggestions!


Hello. Honestly, I would ditch the milk crate and go for plastic wire shelving or something. You can space them out A LOT more than how they are now. Milk Crates are kind of ineffective, in the sense your equipment is still very much clustered together. And the thick plastic grid-wall definitely blocks a lot of air-flow. I set up mine like this:



Honestly I don't even require the fan most of the time my temps stay in the 60s. I am positive you will reduce temps by at least several degrees if you do this. And also move the fan like literally so the plastic face touches the milk crate, to really force the airflow. I noticed that made a big difference with my cards.

As for the difference in temps, all 7950s are definitely not equal. I had several msi 7950s and they could hash around 700 khs no problem. Now with sapphires, they become unstable beyond 640 khs. But the Sapphires definitely kept tons cooler. Even with the exact same card, there can be a big difference. Some people actually repeatedly buy and take back cards, to try to win the "GPU" Lottery. Here is a description I found:

When chip manufacturers like Intel, TSMC, UMC, GF, etc. make wafers, there are slight variations in material quality across the wafer surface, there are local variations in how the lithography, metal vapor deposition, photoresist chemical deposition, etc. are done and this can yield a significant contrast between how good the best chip of a given batch will perform vs how bad the worst chip of the same batch will perform.

To maximize profit, chip manufacturers test and sort chips based on various criteria such as leakage current, power draw at key frequencies, salvageable defects, etc. to decide which product range the chips fit best in. That's binning.

When you buy "K-chips", you are playing the lottery: you are guaranteed a chip that performs at least up to stock K-chip standard but you have absolutely no way to know beforehand how much farther beyond that your specific chip can go under any given circumstances beyond stock conditions. That's the chip lottery. Some i5/i7 3xxxK/4xxxK may max out at 4.2GHz while others may hit 5GHz. Some may require [email protected] to get to a given clock rate while others may require [email protected].



I wouldn't worry too much about it, if you do all of those things, you should lower the temps, and be able to safely increase hashrate.
Bitch you not a Hobbit, right?

Offline CryJim

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Re: Sapphire Radeon 7950 Questions - Different Models
« Reply #10 on: February 04, 2014, 12:28:06 AM »
pguerrerox:

All are Sapphire 7950 cards. Just two variations. But you are correct in that the one running "hot" (black and red) has only a single fan, while the others have two. Would you be interested in optimizing my setting for all cards and the cgminer config? If so, what cost to Teamviewer into to my rig and do so?

I have a box fan blowing from the side (see rig photo). Are you saying it would be more effecient to have a fan blowing down from the top?

Thanks!

Offline naXy

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Re: Sapphire Radeon 7950 Questions - Different Models
« Reply #11 on: February 04, 2014, 12:28:30 AM »
11196-19-20G i have one of these ...

The bads:

1) No VRM temps, vrms are some weirdass model most software not recognize
2) No voltage control for memory
3) Very bad vddc support through only trixx, it's a pain in the ass to change around gets locked to one voltage or crashes etc.

The goods:

1) Can switch to a bios (Blue led on) with 1.094V
2) 690Khash @ 69ºC
3) Hynix memory, mine goes up to 1900 until erroring crashing etc. Doesn't improve much after 1500 tho

Offline LACSTS

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Re: Sapphire Radeon 7950 Questions - Different Models
« Reply #12 on: February 04, 2014, 01:54:04 AM »
Yea the cards with two fans run about 10 degrees cooler.  Your box fan is blowing the wrong way.   you need to put it on the other side so it blows cooler air into where the fan is on not where the hot air is coming out.  That alone will lower the temp on the single fan card because it will be having cooler air to blow.  Right now your blowing one box fan against the hot air coming out of four cards fans.

Eaiest way to undervolt is to get a lower V BIOS.   I have like 13 of the single fan cards you have and I have a 1.09 V BIOS on them vs the 1.25V BIOS they come with.  If you flash the BIOS with a lower V you dont have to worry about using any program to do it.  And use BAMT its alot easier and runs more stable even if you dont know Linux.


Offline pguerrerox

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Re: Sapphire Radeon 7950 Questions - Different Models
« Reply #13 on: February 04, 2014, 01:12:52 PM »
pguerrerox:

All are Sapphire 7950 cards. Just two variations. But you are correct in that the one running "hot" (black and red) has only a single fan, while the others have two. Would you be interested in optimizing my setting for all cards and the cgminer config? If so, what cost to Teamviewer into to my rig and do so?

I have a box fan blowing from the side (see rig photo). Are you saying it would be more effecient to have a fan blowing down from the top?

Thanks!
about the fan, put it on the other side or from the top some how.

about optimizing, sure I can do it.  Will send you a pm if the requested info.