2-way SLI on Maximus V Extreme - best slots 8x/8x or 8x/16x?

[feniks]

I am looking at ASUS MVE manual and it seems that for 2-way SLI ASUS proposes using Intel CPU native bandwidth for both cards (8x/8x natively) using slots PCIe3.0_1 (top first) and PCIe3.0_2B (third from top). I know that switches/bridges may cause some lag, so it makes sense *IF* each of cards doesn't exceed the PCIe3.0 8x bandwidth (I think 670 2GB cards don't but I am unsure of it).
Also this configuration allows for better air flow between cards which probably matters if one relies on air cooling ... I don't, both cards are water cooled.

however I see there is also another config possible which is based on 3-SLI configuration and for 2-SLI it would suggest using both top first and second slots, PCIe3.0_1 & PCIe3.0_2A respectively for x8/16x.

tomorrow I will be installing my second 670 2GB for 8x/8x config for now and I hope it works fine (no lag related to PLX chip switching).

does anybody have some benchmarks comparing same cards and CPU clock (and memory) running 2 cards in each of mentioned configurations?

Thanks!

[stackoverflow13]

did you manage to get SLI? cause when I did it it the second card wouldn't even show in the bios

[JorgeANeto]

stackoverflow13 wrote:
did you manage to get SLI? cause when I did it it the second card wouldn't even show in the bios

In my case, the MOBO never recognize the 1-2b (black slot) arrange whatever I did. Then I decided to put both VGAs in 1st red slot and third red slot and it works immediately.

After a while I managed to put get the 1-2b arrangement working but no difference at all (except higher temps).

[JorgeANeto]

stackoverflow13 wrote:
did you manage to get SLI? cause when I did it it the second card wouldn't even show in the bios

In my case, the MOBO never recognize the 1-2b (black slot) arrange whatever I did. Then I decided to put both VGAs in 1st red slot and third red slot and it works immediately.

After a while I managed to put get the 1-2b arrangement working but no difference at all (except higher temps). The funny thing is the BIOS informing both PCIe slots working at 8x / 8x and not 16x / 8x as I expected (for slots 1 - 3 mounting).

[feniks]

nah, I guess the difference would be there ONLY if the each of cards was able to utilize more than PCIe 3.0 8x bandwidth (equivalent of PCIe 2.0 16x), if they don't then it makes no difference at all 🙂

[stackoverflow13]

I don't under stand 1 + 2b is the normal way install the cards. Slot 4 +1 shouldn't work?? well didn't on mine atleast.

[feniks]

stackoverflow13 wrote:
I don't under stand 1 + 2b is the normal way install the cards. Slot 4 +1 shouldn't work?? well didn't on mine atleast.

strangely it worked in ASUS video on youtube where ASUS employee was comparing 660 card as single and then 2- & 3-way SLI. For 2-way SLI the guy used the sandwiched slots (top part of 3-SLi setup).

[stackoverflow13]

Don't suppose you remember the link for that? Weird how we keep tripping over each other over here Feniks (honest I ain't stalking you LOL)
You mean slot 1 + 4.
I can't use use 6 not enough clearance.

[feniks]

hehe, yeah, I'm still not done with other thread LOL.

here's the link, note where the guy placed cards for 2-way SLI:
http://www.youtube.com/watch?v=UkNgL9VpyfY&list=PL13F5266778601CBA&index=8

stackoverflow13 wrote:
Don't suppose you remember the link for that? Weird how we keep tripping over each other over here Feniks (honest I ain't stalking you LOL)
You mean slot 1 + 4.
I can't use use 6 not enough clearance.

[stackoverflow13]

interesting vid thnx mate. Now it's got me wondering to have another go or not, but from everything said here there does not appear to be any benefit.

[rog-classified]

Hey guys. My question looks stupid i know but have to ask. If i install first gtx680 in pcie x16/x8 (1) first slot and the secant gtx680 in pcie x8 -2b(black) can i use the last pcie x8 (4) for my asus xonar phoebus. Because In MAXIMUS V EXTREME manual 1.2.5(online) , it says - "PCIe 3.0/2.0_x8_2B slot will be disabled when PCIe 3.0/2.0_x16_2A, PCIe 3.0/2.0_x8_3, PCIe 3.0/2.0_x8_4 slots are occupied" xonar phoebus card is already in pcie x8 (4) slot. it meen my 2b slot is disable? cant i mount second card to 2b. im using3 slot card and only can use 2b slot. any one can give me a advice on this cause second card on the way and i don't wanna open it if it cant use. freaking manual make me nuts.