Question for my SLI brothers, maybe crossfire too.

#1 Posted by Klunt_Bumskrint (4159 posts) -

Any of you guys with SLI ever swapped your cards around?

We know that the general consensus is that the top card runs hotter than the bottom card, right?

My 680's and 780's have always been pretty even in terms of temps (top vs bottom). I took my cards out today to dedust them and put them in the other way round to what they were, top in the bottom and vice versa.

Now i'm getting 7 degrees difference at idle and 12 degrees under load and generally they are running warmer.

Anyone fancy giving it a go?

If your temps are a lot hotter on the top card try swapping it around and let me know.

#2 Posted by PredatorRules (8386 posts) -

@klunt_bumskrint said:

Any of you guys with SLI ever swapped your cards around?

We know that the general consensus is that the top card runs hotter than the bottom card, right?

My 680's and 780's have always been pretty even in terms of temps (top vs bottom). I took my cards out today to dedust them and put them in the other way round to what they were, top in the bottom and vice versa.

Now i'm getting 7 degrees difference at idle and 12 degrees under load and generally they are running warmer.

Anyone fancy giving it a go?

If your temps are a lot hotter on the top card try swapping it around and let me know.

Yes the top would run hotter than the lower one because it has less space for ventilation, that's why you'll want to get good case with good ventilation (2 front intakes and 2 top exhausts, the side is not going to help much unless you go with 4 GPUs)

About your GPU config, I guess one of them got better cooling.

You'd want to reapply thermal paste as well.

#3 Posted by Klunt_Bumskrint (4159 posts) -

@PredatorRules said:

Yes the top would run hotter than the lower one because it has less space for ventilation, that's why you'll want to get good case with good ventilation (2 front intakes and 2 top exhausts, the side is not going to help much unless you go with 4 GPUs)

About your GPU config, I guess one of them got better cooling.

You'd want to reapply thermal paste as well.

Ok.

I'm not asking why the top one is running hotter (as obviously I know that). Although mine have about the same ventilation.

Yes I reapply the paste once every so often anyway, again not the issue and one doesn't have better cooling. They are both exactly the same card even running exactly the same bios.

I think you missed my point.

My point IS that they behave differently than each other in the slots. It's almost like they have a favourite PCI slot.

#4 Posted by PredatorRules (8386 posts) -

@klunt_bumskrint said:

@PredatorRules said:

Yes the top would run hotter than the lower one because it has less space for ventilation, that's why you'll want to get good case with good ventilation (2 front intakes and 2 top exhausts, the side is not going to help much unless you go with 4 GPUs)

About your GPU config, I guess one of them got better cooling.

You'd want to reapply thermal paste as well.

Ok.

I'm not asking why the top one is running hotter (as obviously I know that). Although mine have about the same ventilation.

Yes I reapply the paste once every so often anyway, again not the issue and one doesn't have better cooling. They are both exactly the same card even running exactly the same bios.

I think you missed my point.

My point IS that they behave differently than each other in the slots. It's almost like they have a favourite PCI slot.

Then maybe you should DRM the MOBO, maybe one of the slots transfer less power or something or you haven't noticed but one of the PCIe slots is running on x4 instead of equal x8

#5 Posted by Klunt_Bumskrint (4159 posts) -

@PredatorRules: No. The slots are fine.

Anyone gunna have a go at switching?

#6 Posted by 04dcarraher (19954 posts) -

Whaqt is your current case and its cooling config?

#7 Posted by Klunt_Bumskrint (4159 posts) -

@04dcarraher: Why?

#8 Edited by Postmortem123 (7717 posts) -

Run both cards on their own and see which runs the hottest, then put that on the bottom.

I've had many dual card setups with identical cards and their temperatures are never identical even on their own.

I had two reference 7970s and one ran almost 10C hotter than the other when on their own. The hotter one also had locked voltage, strangely.

#9 Posted by 04dcarraher (19954 posts) -

@klunt_bumskrint: Because case cooling can play a role in gpu temps. The top card is more constrictive with fresh air.

#10 Edited by KHAndAnime (14089 posts) -

I had different brands of the same videocard, so it made sense to put the card with the more open 3-fan system on top and the card with the restricted 1-fan system on bottom.

If you have two identical videocards that run at different temperatures, I'd consider the possibility of dust. There's a point where if a videocard collects too much dust, it will always run significantly hotter than it did when it had less dust. A lot of them time you have to open up the videocards and make sure there isn't a dust bunny clogging any air vents.

#11 Edited by Klunt_Bumskrint (4159 posts) -

I'm struggling to explain this aren't I.

Forget dust, ventilation, config of my fans and everything else.

^The cards in this configuration during battlefield 4 both run around 61-62 degrees.^

If I swap card no.1 to the bottom and card no.2 to the top, during battlefield card no.2 runs at around 72 degrees and card no.1 runs at around 58.

Is that clearer?

#12 Edited by PredatorRules (8386 posts) -

@klunt_bumskrint said:

I'm struggling to explain this aren't I.

Forget dust, ventilation, config of my fans and everything else.

^The cards in this configuration during battlefield 4 both run around 61-62 degrees.^

If I swap card no.1 to the bottom and card no.2 to the top, during battlefield card no.2 runs at around 72 degrees and card no.1 runs at around 58.

Is that clearer?

Well now I think I know why the lower GPU is running cooler, you see the PSU? well it's sucking the hot air from the lower GPU which means the lower GPU is getting cooler much faster.

Can't really spot the placement of the front intake but a good lower case fan could do the job well, whether it's 120mm or 140mm.

If the case fan is placed exactly between the 2 GPUs then you should get a 120mm if not go with 140mm

And as before if you do have to place a side case fan you should do it it might help abit.

#13 Edited by Postmortem123 (7717 posts) -

Card 1 may have a better application of TIM or is a less leaky chip or something.

Or runs at a lower voltage?

#14 Posted by Klunt_Bumskrint (4159 posts) -

@PredatorRules said:

Well now I think I know why the lower GPU is running cooler, you see the PSU? well it's sucking the hot air from the lower GPU which means the lower GPU is getting cooler much faster.

Can't really spot the placement of the front intake but a good lower case fan could do the job well, whether it's 120mm or 140mm.

If the case fan is placed exactly between the 2 GPUs then you should get a 120mm if not go with 140mm

And as before if you do have to place a side case fan you should do it it might help abit.

@klunt_bumskrint said:

------>Forget dust, ventilation, config of my fans and everything else. <-----------

The fans are irrelevant to my thread.

@Postmortem123 That's the most feasible post yet.

The TIM was applied at the same time the same way so unlikely to be that. Both OC the same and draw the same volts which is nice, so probably not a leaky chip.

It's just a bit odd you'd expect them to behave the same whether it was in top or bottom.

#15 Posted by KHAndAnime (14089 posts) -

@klunt_bumskrint said:

I'm struggling to explain this aren't I.

^The cards in this configuration during battlefield 4 both run around 61-62 degrees.^

If I swap card no.1 to the bottom and card no.2 to the top, during battlefield card no.2 runs at around 72 degrees and card no.1 runs at around 58.

Is that clearer?

Did you try stress-test benchmarking both cards in both configurations post-dusting and gauging the temperature that way? There are lots of things that can lead to variation in temperatures. If the cards are identical, switching them around shouldn't have any significant effect - at least not one that any one of us could reproduce.

#16 Edited by Klunt_Bumskrint (4159 posts) -

@KHAndAnime: Yup, did a bit of 3dMark results the same but hotter top card with 2 at the top.

#17 Posted by Postmortem123 (7717 posts) -

The software isn't accurate for Kepler voltage so you would have to use a multimeter to check if they were identical or not. It could say 1.21v in software but actually be 1.25v

Though I doubt the voltage difference would be that much and it should only cause a few C difference. Not sure what else it could be.

#18 Edited by Klunt_Bumskrint (4159 posts) -

It's just a bit weird. It's not a problem just thought other people could try swapping their cards and see if they get similar results.

#19 Edited by Postmortem123 (7717 posts) -

Yeah you got golden clockers anyway, so nothing to worry about lol

I've had 2 780s and 5 780tis and not one has hit 1300Mhz.

#20 Edited by zaku101 (4370 posts) -

@klunt_bumskrint:

By chance do both of your PCI-E slots run at 16x when actually in SLI? On some boards they actually clock down to 8x, so slot one 16x slot 2 8x when in SLI. Maybe the two are actually flipping between 8/16x based on slots and one just runs hotter normally when under the same level of stress at the 16x speed. I'd try stress testing them one by one and see what temps you get, that way you know if it's actually a SLI thing or a slot thing.

#21 Edited by kitty (114865 posts) -

I can't swap the top with the bottom and you'll see why with this pic.

http://oi60.tinypic.com/28j88qa.jpg

Dunno if you see the differences in my card sizes. But wouldn't this cause more heat in my case? That said, I don't need to anyways. I applied some Arctic Silver 5 to the top card and it runs 7c cooler. I also got some corsair AF120's and they helped lower my temps some to. I was seeing 82c on really hot days, now I barely crack 70.

My top now hits 70c and the bottom card has never gone passed 68c. It usually is around 62c.

#22 Posted by GTR12 (9813 posts) -

Your cards have favourites, they like their homes and refuse to move to a different home.

#23 Posted by Klunt_Bumskrint (4159 posts) -

@GTR12: It seems that way.

@zaku101: They run at 8x.

#25 Edited by kitty (114865 posts) -

@klunt_bumskrint said:

@GTR12: It seems that way.

@zaku101: They run at 8x.

all of my slots are pci-e 3.0

so i'm running two at 8x which would be basically 2.0 x 16 right?

if I ever got a full tower and went three way cf (course with different cards, I'm aware of this :P) it would be 8,8,4

so the lowest would basically be 2.0 x 8 and that would be fine?

#26 Posted by GTR12 (9813 posts) -

@kitty:

As gamers, we don't need pci-e 3.0, multiple GPU's cant even use pci-e 2.0 @ x16, the power just isn't there yet.

#27 Edited by commander (8249 posts) -

@GTR12 said:

@kitty:

As gamers, we don't need pci-e 3.0, multiple GPU's cant even use pci-e 2.0 @ x16, the power just isn't there yet.

wrong a hd 7970 already gains 1 percent.

#28 Posted by GTR12 (9813 posts) -

@evildead6789 said:

@GTR12 said:

@kitty:

As gamers, we don't need pci-e 3.0, multiple GPU's cant even use pci-e 2.0 @ x16, the power just isn't there yet.

wrong a hd 7970 already gains 1 percent.

I said multiple GPU's and 1% is an improvement? LOL

#29 Posted by Horgen (110180 posts) -

@kitty said:

@klunt_bumskrint said:

@GTR12: It seems that way.

@zaku101: They run at 8x.

all of my slots are pci-e 3.0

so i'm running two at 8x which would be basically 2.0 x 16 right?

if I ever got a full tower and went three way cf (course with different cards, I'm aware of this :P) it would be 8,8,4

so the lowest would basically be 2.0 x 8 and that would be fine?

No, the third one is running x4 at 2nd gen speed.

@GTR12 said:

@kitty:

As gamers, we don't need pci-e 3.0, multiple GPU's cant even use pci-e 2.0 @ x16, the power just isn't there yet.

But why complain? Soon.. As in this year or next year the specs for 4th gen will be released. I bet it is another double up from 3rd gen speed.

#30 Posted by GTR12 (9813 posts) -

@horgen said:

But why complain? Soon.. As in this year or next year the specs for 4th gen will be released. I bet it is another double up from 3rd gen speed.

I'm not complaining, I'm just saying 2 cards or more wont use the full bandwidth of the slot.

A single card is different, I agree with that statement, the thread is about SLI/Crossfire specifically, so I just mentioned 2 cards as that's what we are meant to be discussing.

I think I derailed the thread anyway, sorry guys.

#31 Edited by commander (8249 posts) -

@GTR12 said:

@evildead6789 said:

@GTR12 said:

@kitty:

As gamers, we don't need pci-e 3.0, multiple GPU's cant even use pci-e 2.0 @ x16, the power just isn't there yet.

wrong a hd 7970 already gains 1 percent.

I said multiple GPU's and 1% is an improvement? LOL

Just kidding lol

but you can use pci 2.0 x16 on lga 2011 boards for example, the ones that have enough pci-e lanes

You need four gtx 680's to have a signficant performance with pci 3.0. At this time I don't think it would be a wise decision to invest in a pci 2.0 board though, since cpu's will last long enough.