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Thinking about M.2

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BlueNostromo

Member
Joined
Mar 24, 2015
I was considering getting an M.2 drive, but the only problem is that I am running two 970's in SLI. That puts the both of them in 3.0 x8. Due to the 4790k only having 16 PCIE lanes, adding anything would mean for a decrease in speed for my secondary card. But will running my secondary 970 in 3.0 x4 make a big of a difference?

Also, my board comes with an M.2 x2 slot. If I put a drive in there would that drop my bottom card to x6 or x4 giving me another two lanes to play with? (I would most likely use an adapter to get the full x4 speed)
 

ATMINSIDE

Sim Racing Aficionado Co-Owner
Joined
Jun 28, 2012
x6 is not a valid PCIe configuration, you only get x1/x2/x4/x8/x16.

SLI will not function under x8/x8, you cannot use an M.2 SSD in that motherboard with your current configuration.
 

wingman99

Member
Joined
Dec 10, 2003
I was just wondering when you place a M.2 SSD on Z79 board does it just disable SLI or will both cards run 4x like triple SLI 4x.
 
OP
BlueNostromo

BlueNostromo

Member
Joined
Mar 24, 2015
x6 is not a valid PCIe configuration, you only get x1/x2/x4/x8/x16.

SLI will not function under x8/x8, you cannot use an M.2 SSD in that motherboard with your current configuration.

Didn't know that! Guess I might look into selling these cards, but currently I am trying to sell my laptop...
 

ATMINSIDE

Sim Racing Aficionado Co-Owner
Joined
Jun 28, 2012
I was just wondering when you place a M.2 SSD on Z79 board does it just disable SLI or will both cards run 4x like triple SLI 4x.

Did you mean X79, Z97, or Z77?

Like I just said, SLI needs to be x8/x8 or it will not function.
 

EarthDog

Gulper Nozzle Co-Owner
Joined
Dec 15, 2008
Location
Buckeyes!
Crossfire works with one of the cards at 4x, not sure about two. I would guess yes.

Though, I am not sure how you would get x4 PCIe lanes on each card?
 

ATMINSIDE

Sim Racing Aficionado Co-Owner
Joined
Jun 28, 2012
ok it was z97, Will crossfire work 4x 4x?

Yes, Crossfire will work lower than x8/x8.
Typically there you end up with x8/x4, but note that x4 will cause a decent performance hit (IIRC almost 10%).
 

wingman99

Member
Joined
Dec 10, 2003
Crossfire works with one of the cards at 4x, not sure about two. I would guess yes.

Though, I am not sure how you would get x4 PCIe lanes on each card?

It's ben a long time since I looked into this. I think its like video memory both cards run at the lowest denominator even though the top card can use 8x lanes.