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Best option for 2-way SLI?

Inaharry

Inaharry

Inaharry

Associate
Joined
3 Aug 2004
Posts
252
Hi,

After spending the last week looking into this and getting nowhere, I thought I'd ask the experts here! :)

I've got 2 x GTX980 HOFs waiting for me to make a decision on the rest of an i7-4790K based build, but I need to know which is better for a 2-way SLI setup, (I don't plan to add any more cards in the future....)

Which would give the best performance on OC cards like the HOFs, running x8/x8 or x16/x16 with a PLX chip and its latency?

Thanks!
 
Nothing wrong with PLX boards tbh... Latency you will never notice even if its there, its so low you will never see or feel it.

What a PLX board does give you though is flexibility on where you install your GPUs for max air flow etc.. If you using Reference GPUs this wont really matter, but if you using after market GPUs then you good.

I use a PLX Chip board and its great..
 
Make sure the board has plenty of space between the cards, if they get too hot this will effect performance a lot more than choosing PCI-E3.0 x8 or x16
 
Kaapstad said:
Make sure the board has plenty of space between the cards, if they get too hot this will effect performance a lot more than choosing PCI-E3.0 x8 or x16
Click to expand...

This!
And This is also why it can be worth spending the extra on a PLX Chip... It really is worth it when it comes to cooling multiGPUs..
 
PLX chip actually lower perf than 8x 8x native. Get the board with best spacing this is a must for air.
 
8 Pack said:
PLX chip actually lower perf than 8x 8x native. Get the board with best spacing this is a must for air.
Click to expand...

Really? I noticed no difference coming from 8x-8x Asrock z68 to this board 16x - 8x

I got same scores in my testing.. only thing I gained was lower top GPU temps..
 
8 Pack said:
PLX chip actually lower perf than 8x 8x native. Get the board with best spacing this is a must for air.
Click to expand...

Well considering most boards run x8/x8 native through the CPU without going through the PLX chip I would say that's strange.

My board goes direct to the CPU with 2 cards installed and only goes through the PLX chip once 3 or more slots are in use.
 
Thanks for all the replies, they've been really helpful. :)

Airflow between the cards is going to be important because my new case will be the Corsair 760T which like my Obsidian 650D doesn't have a side fan. I've noticed that motherboards with a PLX chip have a larger distance between the two x16 slots than ones without because the x8/x8 non-PLX boards tend to have a x1 slot above the first x16 slot which moves the graphics cards closer together.

I (think) I've narrowed my choice down to two boards, the Gigabyte Z97X Gaming G1 WIFI BK and the MSI Z97 Gaming 9 AC

The audio looks good on both boards, which is important because I'll be using a Sennheiser PC-360 headset a lot of the time. The MSI doesn't have a PLX chip so will run at x8/x8 natively, but the x1 slot at the top will mean the two GTX980 HOFs will be quite close together and as they're not reference design, are likely to get quite hot. The Gigabyte, being a PLX enabled board, has better spacing between the cards, but will be potentially slower because of the added latency.

I just want to make the right decision to make the most of buying pre-overclocked cards. Any thoughts about the motherboards I'm considering for this setup or any other suggestions?

Thanks again!
 
Thanks for the suggestion, that's what I've done. I've ordered the Gigabyte mainly for that reason. As 8 Pack said, I know that I'll get a performance hit because of the PLX, but I'm hoping that the OC on the HOF cards will make up for it and the extra cooling space should, I hope, stop them from throttling because of heat.

Thanks again. :)
 
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