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Author Topic: In a dual graphics configuration, which graphics card hates life more?Top or Bot  (Read 1179 times)
ensign_lee
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July 13, 2011, 06:16:29 PM
 #1

Hey y'all,

Conceptual question. I have a two ATI cards. Which card will hate life more (i.e. be hotter), the card on top or the card on bottom?

I thought it would be the card on the bottom since it is closer to the bottom of the case and the top card has all the air above it, but I'm starting to think that's not true based on temps in my machine.

Will the top card end up hotter than the bottom? Or vice versa?

And if so, why?
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BitPorium
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July 13, 2011, 06:22:01 PM
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The top card will be hotter because of the obstructed airflow that it gets because of the space between cards.
AngelusWebDesign
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July 13, 2011, 06:33:20 PM
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Always the top card.
XRcode
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July 13, 2011, 07:53:20 PM
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In my triple 6970 system the middle card is always 10C hotter then the other two
Due to the shitty design of the gigabyte triple fan cards not exhausting any hot air out of the case.

My visionteks with single fans stay much much cooler in the other system
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July 13, 2011, 07:55:12 PM
 #5

Theoretically - top card.

But I was tracking temperature of my 2 x 6990 video cards and cannot really say, which one has higher temperature.
All cores are behaving strange — every core randomly gets higher temperature during the 2-3 days. So they are changing each over in high temperature...

Anyone can explain this?

Sjalq
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July 13, 2011, 08:13:08 PM
 #6

GPU 0 always seems to run the hottest.

Club 3D 6990s have a great design, air is sucked in on the flat side of the card and exhausted out the sides (back of case and front), so there is very little feeding of hot air from one card into another. If you have a MSI 890FXA-GD70 you should fit in 3 cards comfortably if you remove the PSU from the case (if you have a bottom mounted PSU)

Cheesy mine mine mine mine mine mine mine Cheesy
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ensign_lee
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July 13, 2011, 10:04:05 PM
 #7

Seems like I was wrong. Top card has a harder life.

Guess I'll switch the position of my 5870 and 5850 then, since the 5870 was on top and is running at 86 Celsius when mining  (at 96% fan!) while the 5850 underneath enjoys 70 degree temps at 52% fan.
bcpokey
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July 13, 2011, 11:33:42 PM
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Seems like I was wrong. Top card has a harder life.

Guess I'll switch the position of my 5870 and 5850 then, since the 5870 was on top and is running at 86 Celsius when mining  (at 96% fan!) while the 5850 underneath enjoys 70 degree temps at 52% fan.

It's always about airflow. Which is why middle cards typically tend to be hotter when you go above 2 cards. They have a hot card on top of them with poor airflow radiating heat and disallowing it to radiate efficiently, as well as additionally having it's own airflow reduced by a card below it (also radiating heat into the area it takes it's air from).

If you can figure a way to space the cards a little bit (risers, or plastic spacers) and/or force cooler air in between the card it can help a LOT. From my own experience when the room ambient was about 80F the cards ran hotter and louder than when the room ambient was 65F, without any other change to the setup. Cooling is a PITA.
BitPorium
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July 13, 2011, 11:47:49 PM
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Seems like I was wrong. Top card has a harder life.

Guess I'll switch the position of my 5870 and 5850 then, since the 5870 was on top and is running at 86 Celsius when mining  (at 96% fan!) while the 5850 underneath enjoys 70 degree temps at 52% fan.

It's always about airflow. Which is why middle cards typically tend to be hotter when you go above 2 cards. They have a hot card on top of them with poor airflow radiating heat and disallowing it to radiate efficiently, as well as additionally having it's own airflow reduced by a card below it (also radiating heat into the area it takes it's air from).

If you can figure a way to space the cards a little bit (risers, or plastic spacers) and/or force cooler air in between the card it can help a LOT. From my own experience when the room ambient was about 80F the cards ran hotter and louder than when the room ambient was 65F, without any other change to the setup. Cooling is a PITA.
Ambient temperatures make a huge difference. The lower the ambient the more energy it can absorb. a 20 F change is not insignificant. I have my fans all at 85% and they only reach 60c, because i make sure my ambient stay from 65-70f. But i have to agree with the middle being hotter. But proper airflow will fix that. Just make sure that there is enough positive air pressure to allow the fan to suck that air in, I prefer blower style cards for better cooling, but with the open style, i just like to have a strong exhaust fan. I like to keep things neutral, I usually do 2x65cfm intake fans right behind the cards and one 110-120cfm exhaust at the top. Seems to keep things manageable.
ensign_lee
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July 14, 2011, 12:33:17 AM
 #10

Hmm, interesting. I switched my 5870 to be the bottom card, and it promptly started hating life even more at like 96 degrees! O.o Cheesy

So...back to the top it goes. Oh well. I guess 90 isn't *that* bad hehe.
bcpokey
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July 14, 2011, 01:22:21 AM
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Well as mentioned, ambient makes a lot of difference, make sure you have adequate case flow. I have a rig with 4 5870s all shoved together like sardines. They are currently running at...82C for the hottest (middle) card, with a fan speed of 54% (my poor ears can't take much more than that).
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