2x7990 or 4x7970

[random2]

Thank you for answer. I will try it.

[random2]

Still trying to solve the problem with cooling. I tryed a lot of different options, but there is still no final decision. Please, share your experience in such matters:

1. What is the maximum temperature is normal for video cards? At the moment, after attempts to place 3 of 4 cards (one not connected specifically) temperature floats from 83 to 95 degrees.
2. If I place the GPUs in a separate unit, as it will be better than it is now - all in one, but the spacious big case?
3. I can not find long CrossFade cables to connect the video cards. If I do not use them, it will not affect the speed?

Thank you.

[epixoip]

1. "normal" is subjective, but anything below ~ 83 is ok. 84-88, keep an eye on things. 89-90, time to start worrying. 91+, kill the load and let it cool. 95 is definitely critical.

2. not sure what you mean by this, but you need adequate spacing between your gpus. unless you have some serious server fans in your chassis that push massive amounts of air, your gpus should not be side-by-side.

3. you should not be using crossfire. so ditch the cables.

[random2]

Thank you epixoip.
Now the temperature after working 30-40 mins floating between 83-95. So I need to do something with it.

2. Regarding space - now I have ~8 cm between them.
Regarding fans - I have one 200 mm fan on top of the case and one on front. Also 4x120 mm fans on the side of the case. And I'm surprised that they do not really helps.

I see that if I place the GPUs out of the case, this should greatly reduce the temperature.
blandyk in this thread wrote about a similar case. What would you say - its true? Temperature is about 66 *C on his HD5870.

[KT819GM]

Maybe it's stupid question but: you regulate your fans by yourself or it's on automatic? For hash cracking you need to put all cards manually depending on ambient temperature and your case specs. So try to put them manually on ±80% and see if temp grows or drops. Also front fan is blowing air inside or sucking out? Side fans also sucking or blowing air onto cards? with so much fans you can possibly make vertex'es inside case and because of that can make everything even worse because you slowing down card fans and also not giving them enough cool air.

[random2]

> you regulate your fans by yourself or it's on automatic?
I set manually the speed to 100%. But I see that 100% starts to work when the temperature reaches ~70 degrees and above. Also I tryed automatic, but manual I think is better.

> front fan is blowing air inside or sucking out?
Front fan blowing air inside and top fan sucking it out. Side fans blowing air onto cards.

> with so much fans you can possibly make vertex'es inside case
Sorry for my english, can you describe in more detail what do you mean - "vertex'es"?

I think over the decision to place the cards in a single small case with good ventilation and plenty of space between them (There is no way to place cards outside of the case, I want a universal safe option). Is there any ready-made solutions for this? Maybe a small case like microATX? But there are many questions - is there be enough length of risers, does it help or not, ...?

[epixoip]

I set manually the speed to 100%. But I see that 100% starts to work when the temperature reaches ~70 degrees and above

this isn't right. even if the temp is 20C, if you set the fan speed to 100%, the fans should immediately jump to 100%. there shouldn't be any delay.

I think over the decision to place the cards in a single small case with good ventilation and plenty of space between them (There is no way to place cards outside of the case, I want a universal safe option). Is there any ready-made solutions for this? Maybe a small case like microATX? But there are many questions - is there be enough length of risers, does it help or not, ...?

no no, you have the completely wrong idea. you cannot have all that heat in a small case! you need a bigger case with more fans and more airflow. or better yet, you need to build a custom open-air chassis.

[random2]

Thank you epixoip, I intalled very loud fan with high speed - now it's better (but now I'm using only 3 GPUs).