Bitcoin Forum

Hello,

I have been planning on getting a new rig with 5 * 7970 on it...

I have multiple GPU's in my cart...

http://www.newegg.com/Product/Product.aspx?Item=N82E16814125439

vs

http://www.newegg.com/Product/Product.aspx?Item=N82E16814125414

and I also saw a few Sapphire 7970....

but based on experience... can somebody chime in? which GPU should I get?

I got 6 MSI R7950 OC edition and even though people saying they are good... well based on my experience I am only getting 550+khs on each...

so I am thinking of moving to Gigabyte or Sapphire.. but there are too many 7970 from each brand...

any help will be appreciated... I did do a "one" week search about this... and still not convince which 7970 to get...

Thanks

I have that Gigabyte 7970 WF3 GHz Edition, stock OC of 1100MHz, and I can OC to 1200MHz and get 722MHs with no problems. I don't have a high ASIC quality, either. I have one of the earlier ones, that's voltage unlocked, but IDK if the newer ones are unlocked. It doesn't do that great for LTC, tho, and I can barely get 600KH/s on a good day.

If you're ever planning on switching to LTC at any point, get that Gigabyte 7950. It's one of the best LTC cards there are, and uses the same cooler as the 7970, so it stays nice and cool.

well yeah.. it is for LTC mining... I forgot to mention that...

anyway... I do not see any WF3 on 7970.. only on 7950?

Ya if you're going to be switching to LTC, go with the 7950.

Sorry, WF3 = Windforce 3 (http://www.gigabyte.com/MicroSite/275/3x-Triangle-Cool.html), and is the triple fan heatsink design Gigabyte uses on their high end cards.

I mine LTC on both sapphire and gigabyte (WF3) cards, and the gigabyte ones are infinitely better.

I get about 720khs per card (vs about 660 on the sapphires) with the following settings:

Core: 1045
Mem: 1500

Concurrency: 8192
Vectors: 1
GPU Threads: 2
Worksize: 256
Intensity: 13


I wish I had only bought the WF3 cards..

I have 3 rigs all with Sapphire 7950's.  Specifically the 20G model.


I get 640-650 KH/s mining LTCs.

I use these settings.

Core 1100
Mem 1500
V 1.09
Powertune 20
Intensity 20
TC 19000
Threads 1


If you do the math the 7950's are a lot better.

Oh yea. On Windows you can set the V to whatever you like. But on BAMT or Linux you have to flash a BIOS to the cards to get them to run at 1.09 V.


But the W difference between 1.09V and the stock 1.25V is a lot.

What model? Those can't be the GHz edition cards, are they?

They are the GHz cards:

http://www.newegg.com/Product/Product.aspx?Item=N82E16814125413


are the ones I bought.

Can you post some screenshot pls...

I have searched and a few people are having trouble with this:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814125413

so I am not really sure which one to get..

also base on this site:

http://coinpolice.com/gpu/

the best for scrypt is:

MSI Radeon HD 7970 Twin Frozr OC Boost Edition

should I just get 5 of:
MSI Radeon HD 7970 Twin Frozr OC Boost Edition ?

Why not just hunt down a used 6690 instead? Guaranteed at least 800 kh/s out of the box. 900kh/s with some overclocking.

Why? Cuz they're expensive, and you can only put 4 in a computer, tops. You can get 6 7970s working if you do it right, and they're easier to cool.

My gigabyte 7970's get 720-740.  These ones are nice because they have no shroud on top.  This means that you can put a small case fan on top and it does a great job of cooling these cards down when they are close to each other..

I have the same card. Problem is it gets really hot. The 7970 WF3 Ghz Editiotn should not be in a case when overclocked. But you can amp it even more. Outside of the case it started crashing at around 1285 for me. Problem was that inside a case, it gets ridiculously hot even at lower temps.

You cannot undervolt it, which will ruin your day, if you want to save electricity costs. This baby needs to be run in the wild on maximum power to make sense.

Ya I'll agree with that. The fans do a great job at moving the heat away from the card, but in a case, it just recirculates the hot air like all hell (pun not intentional). I've found I get better temps by removing the side of my case, but then I don't filter dust as well, so I put it back on. If your case has any side slots for fans to blow on the GPUs, make sure you install the fans so they blow out, venting the hot air from the GPUs. I also found this dropped the temps by a deg C or two.

These cards really were meant to be in an open-air rig, overclocked to all hell. I couldn't get mine much past 1200 while still stable, but I have a somewhat low ASIC quality.

I have so far installed 1-2 outside blowing 120mm fans. I was thinking about installing another one and more at the front for airflow...

What card are those specs specifically referring to?  I'm curious as to how you are getting 720khs out of a card on Intensity 13/TC 8192.  

Side question, I have a Sapphire Vapor-X 7950 which I seem to peak at 630khs.  Would a comparable Gigabyte 7950 be that much of an upgrade on performance?

What that guy posted is a 7970. This is a thread about 7970's after all, not 7950's.

They're about the same price as a 7970. I'd say 6990's are easier to cool since they have the enclosed shroud design. You have a point about the number of cards though I don't see many people with 6 cards on one board.

Which is why I said it was a side question and wasn't comparing his 7970 to my 7950.  I want to know which 7970 specifically.  And there's been talk about certain 7950s being better than others, I wanted to hear further on people's experiences with this.

Im planning to get Sapphire HD7970 Vapor-X 3gb GHz edition

who has that kind of gpu and how's the hashrate of it so far?

I have a Powercolor 7970 that gets 760 kh/s.

I could not get my Gigabyte 7970 OC stable past 600k after hours of tweaking, with your settings I'm sitting on 630+

Thanks!

can you provide proof pls?

You will get 500kh/s on a good day.

There's no such thing as proof, but the fact that other people are getting similar numbers here https://github.com/litecoin-project/litecoin/wiki/Mining-hardware-comparison#wiki-ATI_AMD_GPU (https://github.com/litecoin-project/litecoin/wiki/Mining-hardware-comparison#wiki-ATI_AMD_GPU)s is pretty strong evidence.