Mining LTC with 7790

[muto]

Hi all,

I recently bought two 7790 and want to scrypt mine with it. Currently I'm using cgminer 3.1.1.

Stock (1075/1600) I got 200KH/s of each of the cards. Then I tried to play withe clocks and found out, that I get 245KH/s when underclocking it to 830/1500. While I´m willing to believe that underclocking of the GPU doesn't affect the performace, I'm really wondering that it even improves the performance. Since the RAM is very importent for scrypt mining I'm wondering even more, that underclocking the RAM is also improving the performance.

I found several (older) threads of people which experienced the same. The only thing I can imagine is, that the driver is really bad (since the 7790s have their own driver which is a seperate download and exists beside the 7xxx driver).

Is anyone able to explan this and/or does have any idea for improvement of the performance.

Cheers,
Muto

[ZetaOS]

Ok

[HellDiverUK]

Do you mean 7790 or 7970? 

If you do mean 7790, wow did you buy the wrong cards.  7950 is THE scrypt mining card - they do 550KH/s at relatively low power use, and they're cheap.  I got mine for about £180 used off Fleabay.

[crazyates]

Sctypt is very timing sensitive, so the ratio of core/memory clocks is very important. You should find your highest ram clocks, and then work your core clock down until you find the proper ratio. The cgminer scrypt-readme explains all this.

[Walking Glitch]

Sctypt is very timing sensitive, so the ratio of core/memory clocks is very important. You should find your highest ram clocks, and then work your core clock down until you find the proper ratio. The cgminer scrypt-readme explains all this.

I found with the 6850 in my main computer that overclocking the hell out of the cores, and slightly lowering the memory clocks (from a total of 4GHz, or 1GHz 256bit down to 3600MHz total or 900MHz per 64 bit channel) yielded the best rates. wtfsauce

[skleven]

Do you mean 7790 or 7970? 

If you do mean 7790, wow did you buy the wrong cards.  7950 is THE scrypt mining card - they do 550KH/s at relatively low power use, and they're cheap.  I got mine for about £180 used off Fleabay.

Wel not really.. You get around half the mh/s, it uses less that half the power and cost less than half of the 7950.

[HellDiverUK]

But therefore takes twice as long to do anything, which is a bit of a problem because difficulty goes up.  You need as fast as you can the soonest you can to make the same amount of coins.

Double the speed, double the price, double the power will make it's ROI back quicker than the slower card.  Plus the 7950 will have a better resale value when you're done with it - heck I sold my 6970 cards for more than I paid for them, after using them for a year hashing.

[muto]

7950 is THE scrypt mining card - they do 550KH/s at relatively low power use, and they're cheap.  I got mine for about £180 used off Fleabay.

Currently I get 490 KH/s at lower power consumption and I guess there is room for improvement. This is why I opened this thread. In fact I made the decission for the two 7790 because they are much more quiet compared to the 7950. This is very important in my case. But I didn´t want to discuss the 7790vs7950-thing here.

Sctypt is very timing sensitive, so the ratio of core/memory clocks is very important. You should find your highest ram clocks, and then work your core clock down until you find the proper ratio. The cgminer scrypt-readme explains all this.

Thanks for that great post. It explains everything I wanted to know. Will test it that way

[lishbtc]

My advice is to tune/test, rinse/repeat.  Put in a few hours to find the sweet spot - it's worth the effort.

For example for my first month of mining after building my rigs (2 rigs with 3x7950s each) I was averaging about 550kh/s per card with everything stock.

These days I mine at around 620kh/s per card AND use less power.

FWIW:
Stock 850/1250 @ 1.25V.
I overclock at 1050/1575 & undervolt @ 1.063 for stable mining (I can push more but only if I don't mind cleaning up after the odd driver crash).

[muto]

Ok, I played a little bit with several configs of the cgminer. The readme seems to be really nice, but nothing helped to improve the hashrate

For example:

--thread-concurrency:
This tunes the optimal size of work that scrypt can do. It is internally tuned
by cgminer to be the highest reasonable multiple of shaders that it can
allocate on your GPU. Ideally it should be a multiple of your shader count.
vliw5 architecture (R5XXX) would be best at 5x shaders, while VLIW4 (R6xxx and
R7xxx) are best at 4x. Setting thread concurrency overrides anything you put
into --shaders and is ultimately a BETTER way to tune performance.
SUMMARY: Spend lots of time finding the highest value that your device likes
and increases hashrate.

Currently I´m using 8000, which is not a multiple of my shaders (896). I tried 8096 and 7168 then and got about 20Kh/s less on both 

However, I continued to try to get better results and played a little bit with MSI Afterburner. Finally I managed to get stable 260 KH/s out of each card at 845/1800. Since the temperature jumped to 63/71° (the noislevel went up too ofcourse) from 53/62°, I'm back at 830/1500 and 245KH/s now. I'm wondering if there is a trick to get the upper card a little bit cooler?

Will continue to search for another sweetspot tomorrow. Any help or suggestions are very much appreciatet

[jdebunt]

well i have my 7970 at 910/1095, maybe try that & work your way upwards to see where you can get to

(my settings get me 630 khash btw, it's also undervolted)

[spoid]

Do you mean 7790 or 7970? 

If you do mean 7790, wow did you buy the wrong cards.  7950 is THE scrypt mining card - they do 550KH/s at relatively low power use, and they're cheap.  I got mine for about £180 used off Fleabay.

Wel not really.. You get around half the mh/s, it uses less that half the power and cost less than half of the 7950.

plus you can combine them with the ATI never settle reloaded keys which are still far from worthless.
However, as always, in a country where electricity is expensive, you need lots of hashpower per rig to make up for mainboard/CPU... so you'll probably need 7 of the 7790s to even make a cent of profit in germany

[eule]

I still think a rig with 4-5 used 5770 would be both cheap and efficient. I mine on one and am quite happy.  
1MH for 200€ should be very possible that way. Of course they use a bit more power than their 7xxx counterparts, still less than 500W for 1MH.

[muto]

No offense intended but the topic here is the 7790 and not another cards.

[eule]

OK, just wanted to show the 7950 crowd that "slow" gpus can be a smart choice.  

[muto]

No problem, it's just a lot of people which throw card xxxx in the game here and this thread should be for the 7790

Is there noone out ther mining scrypt with the 7790? Does anyone know how to change vcore for that card? MSI Afterburner is not able to do so.

[Aureliusy]

I mine with 14 7790. They all do 245/246 max  (setting 830/1500 -20 power afterburner)
I tried Motherboards that should support >7 GPU.  I could only get 5 cards to work under windows 7 or 8. and 13.6 beta 2 drivers
One of the 5 GPU's often did fail (Tried auto and high fan setting) , so I have 4 max GPU for one MB now and I do  not have to babysit the cards any more. I did not use powered Risers

[Aureliusy]

Afterburner alternatives (For maybe unlocking vcore)

Sapphire TRIXX
https://www.sapphireselectclub.com/ssc/TriXX/TriXX.aspx

ASUS' GPU TWEAK
http://www.asus.com/Graphics_Cards/Features/GPU_Tweak

[muto]

Thanks for the links to Asus and Sapphire, will try it and report back.

I mine with 14 7790. They all do 245/246 max  (setting 830/1500 -20 power afterburner)

That is very interesting. Did you try using 845/1800? Or any other value which runs with higher hashingrate? I will let it running overnight with the higher clock to test if it is really stable. If everything works fine, I will try to undervolt tomorrow to get the temperature to a better level.

What temperatures do you have on your cards?

I tried Motherboards that should support >7 GPU.  I could only get 5 cards to work under windows 7 or 8. and 13.6 beta 2 drivers
One of the 5 GPU's often did fail (Tried auto and high fan setting) , so I have 4 max GPU for one MB now and I do  not have to babysit the cards any more. I did not use powered Risers

I also have had problems with the second card while I had it in a slower PCI-E slot (to get more space for the cooler). Ended up in slower performace and also crashes. So I put it back in the PCI-E x16 slot and everything works fine. But I have less space for the cooler and nearly 10° more :/

[muto]

Everything was stable this night:



Since I want to have lower temps I decided to run one Card with 828/1500 and the other Card with 845/1800 at 63/67°.

The Asus tool is the only tool (of this 3) which is able to change voltage. But it gave me a lot of driver crashes even at stock settings. Because of that i uninstalled it and I'm back withe the Afterburner. Will it leave for the time beeing with this settings.