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SLI card Placement

Last response: in Graphics & Displays
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July 30, 2010 4:11:13 PM

Hi Guys,

So I just got a new motherboard, the MSI nf980-g65. It is touted as a 3way SLI board.

I also purchased 2 PNY 9800GTX+'s for a 2way sli setup. The mobo supports SLI in the following configurations:

2way- 16x16x0
3way-16x16x8

So basically if you run something in the third pci-e slot you get only 8x. How noticeable is this drop in pcie lane bandwidth?

My setup of the 2 cards in the first 2 pcie slots covers the south bridge (MCP) COMPLETELY. Blocking it off from 95% of the air circulation. I have seen this thing hit 100C in heavy gaming (this is with me opening my windows to bring in cold air, ambient room temps are 60c). I have placed a spot cool fan on it, but it is so packed in behind the Graphics cards it doesn't help.

I am thinking of moving the second card to the third pcie slot.

I am thinking that will make my setup look like this:

16x0x8

So there will be a slight decrease in performance. Has anyone else tried this? I would assume it won't damage the motherboard in this configuration, even though it is not supported?

I just can't continue to place these 2 monster cards so close that there is only a 1/4 inch gap between them, the heat is crazy and even with the best case airflow it still runs super hot.

I have found many people with similar questions but have not found a satisfactory answer. Have read the graphics and SLI Faq here, so just wondering if anyone else has experienced this or maybe wondering the same thing....

More about : sli card placement

a c 169 U Graphics card
a c 136 V Motherboard
July 30, 2010 4:30:22 PM

Hello and welcome to the forums
Running a card at 8x won't make much of a difference unless you play at very high resolutions.If you play at resolutions up to 1920x1200,then the difference isn't noticeable, if you play at higher resolutions,then there may be a 5-10% performance drop
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a b U Graphics card
a b V Motherboard
July 30, 2010 4:48:11 PM

It might scale to X16/X0/X16.

Though the southbridge is really hot, regardless of the GPUs, remove the heatsink and put some decent TIM on it.

By the way: "ambient room temps are 60c" are you alright? LOL
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a b U Graphics card
July 30, 2010 5:05:11 PM

UnseenGuardian said:
ambient room temps are 60c


i think you mean 60 f, cause if your room is 60c (~140 f) then you have bigger things to worry about then your GPUs overheating.

in regard to your question, you won't see a large hit on PCIe 2.0 x8 in SLI (maybe 5-10%)
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a c 169 U Graphics card
a c 136 V Motherboard
July 30, 2010 5:27:20 PM

Timop said:
It might scale to X16/X0/X16.

Though the southbridge is really hot, regardless of the GPUs, remove the heatsink and put some decent TIM on it.

By the way: "ambient room temps are 60c" are you alright? LOL

If a motherboard supports MultiGPU at 16x16x8x,then if the third slot is occupied(even if the second slot is empty),it will operate at 8x AFAIK
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July 30, 2010 5:54:20 PM

OOOPS, yes I meant 60f. What, you guys didn't see my build thread about "How to run your pc in the sauna for best performance"??

Thanks for the replies guys. Yeah maybe I will just try it out and do some benchmarking and see what happens.

My biggest concern right now is just to not screw up my new mobo, but I wouldn't think that could happen (dumb question I know but I've always populated PCI slots from cpu on down, never skipped one before).

If anyone else is curious, once I find a good benchmark program and try it out I will post results.

Just was wondering if anyone else had tried this or experienced this too.

Should have bought an XL-ATX mobo, or an E-ATX or whatever they call that. I have a monster computer case but the graphics cards are packed in there so tightly its just stupid.
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a b U Graphics card
a b V Motherboard
July 30, 2010 6:10:26 PM

Maziar said:
If a motherboard supports MultiGPU at 16x16x8x,then if the third slot is occupied(even if the second slot is empty),it will operate at 8x AFAIK

There are certain boards that scales adaptively though. I think EVGA and the Intel P55s IIRC.
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a b U Graphics card
July 30, 2010 7:36:40 PM

UnseenGuardian said:
OOOPS, yes I meant 60f. What, you guys didn't see my build thread about "How to run your pc in the sauna for best performance"??


Oooh!! You're doing fairly well if your Sauna is 60C. According to the rule of 200, you want your ambient temp in F plus humidity to equal 200! So with 140F, you need 60% humidity. :)  You're on the right track!
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a c 169 U Graphics card
a c 136 V Motherboard
July 30, 2010 7:37:01 PM

I see
I was talking about X58 chipsets though,(motherboard like P6T series)
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July 30, 2010 8:07:14 PM

jerreece said:
Oooh!! You're doing fairly well if your Sauna is 60C. According to the rule of 200, you want your ambient temp in F plus humidity to equal 200! So with 140F, you need 60% humidity. :)  You're on the right track!


Yeah... Why do you think they have those signs saying: "Don't pour water on the 'rocks'". It's because thats not rocks, just a badass heatsink for a cpu. Didn't u know they use computers to generate heat in sauna rooms?

Prove me wrong.. PROVE ME WRONG.

:) 
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a b U Graphics card
July 30, 2010 9:00:24 PM

UnseenGuardian said:
Yeah... Why do you think they have those signs saying: "Don't pour water on the 'rocks'". It's because thats not rocks, just a badass heatsink for a cpu. Didn't u know they use computers to generate heat in sauna rooms?

Prove me wrong.. PROVE ME WRONG.

:) 


This is what we call a "Dry Sauna" - As opposed to the more traditional use, where you do in fact drizzle water over the rocks and get that awesome flash of steam. Mmmm

I'll tell ya though, with so many performance level motherboards on the market, board makers really need to start looking at more effective cooling solutions for the chips on the board. Some boards come with great cooling, but a lot of the time you have to be concerned with the cooling solution and whether or not it blocks the CPU Heatsink, GPUs, etc.
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July 30, 2010 11:56:37 PM

jerreece said:
This is what we call a "Dry Sauna" - As opposed to the more traditional use, where you do in fact drizzle water over the rocks and get that awesome flash of steam. Mmmm

I'll tell ya though, with so many performance level motherboards on the market, board makers really need to start looking at more effective cooling solutions for the chips on the board. Some boards come with great cooling, but a lot of the time you have to be concerned with the cooling solution and whether or not it blocks the CPU Heatsink, GPUs, etc.


OK so on that note...

I put 1 card in slot 1 (pcie2) and the second card in slot 3 (pcie6).

It didn't even recognize the second card. Strange.. and lame. I guess you can't do 16x0x8, you have to do either 1 of the two choices offered by the manufacturer.

OK so I guess my only option is to have them both touching each other and completely blocking off the SB/MCP.

Interestingly enough, I did find out that with only 1 card in the slot, MCP temps are unchanged even with massive air blasting its heatsink. It shoots right up to 90-94c, even with only being on for 1 min, right after booting to windows on a cold startup.

I have seen other threads with people saying that "MSI/nvidia shipped the chipset with a faulty temp sensor", but it can just as well be bad thermal contact. It definitely feels cold when reported as 93c so that doesn't make sense...

Im going to pull off the heatsink and put some AS5 on it and see if that helps. If not, then its a bad sensor :) 
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