running a m.2 drive and 980 at 16x?

[TheZuluWarrior]

May be a stupid question.

But if i wanted to run a 980 and a m.2 pci-e slot SSD im right in think i would need the motherboard to have the bandwidth to run them both in 16x?
or it would split 8 each? also if so any suggestions on the motherboard? something around £100? or is that just to low?

or would it be worth waiting for sata express?

im getting all confused.

thanks for the help in advance. 

[H4nn3s]

A m.2 drive would run at 4x all the time. But with Z97 your gtx 980 would run at 8x.

[Sakkura]

It depends on the motherboard.

 

Bear in mind that there are 16 PCIe 3.0 lanes from the CPU, and 8 PCIe 2.0 lanes from the chipset. So depending on where the M.2 SSD gets its PCIe lanes from, it may or may not force the GPU to run on 8 lanes instead of 16 (though 8 lanes is still fine).

[jscho]

A m.2 drive would run at 4x all the time. But with Z97 your gtx 980 would run at 8x.

 

Do m.2 drives run off the CPU PCIe lanes or the chipset?

OP: Either way, it doesn't affect your performance at all. M.2 runs at PCIe 2.0 4x. This will have little impact on your 16x PCIe 3.0 GPU

[H4nn3s]

I think it depends on the motherboard, but i am not sure.

[TheZuluWarrior]

Do m.2 drives run off the CPU PCIe lanes or the chipset?

OP: Either way, it doesn't affect your performance at all. M.2 runs at PCIe 2.0 4x. This will have little impact on your 16x PCIe 3.0 GPU

hang on im still wrecking my head here. 

i have found m.2 drives that run off pci-e 3.0 for example. the samsung SM951, and im guessing that depends on the motherboard. i would need one that has a pci-e 3.0 m.2 slot? or are all m.2 slots able to use pci-e 3.0 and 2.0?  but! i would also need a board with 32x coming from the cpu? to the pci-e lanes? 

and if so do they even make that? i mean why would they give you the option of having a pci-e 3.0 m.2 drive that cuts the bandwidth of your gfx card? it just seem insanely stupid to me?

[jscho]

hang on im still wrecking my head here. 

i have found m.2 drives that run off pci-e 3.0 for example. the samsung SM951, and im guessing that depends on the motherboard. i would need one that has a pci-e 3.0 m.2 slot? or are all m.2 slots able to use pci-e 3.0 and 2.0?  but! i would also need a board with 32x coming from the cpu? to the pci-e lanes? 

and if so do they even make that? i mean why would they give you the option of having a pci-e 3.0 m.2 drive that cuts the bandwidth of your gfx card? it just seem insanely stupid to me?

 

Righto haha. I'm gonna try to make this a simple as possible haha. I'll highlight the important, keep in mind, parts in bold.

M.2 runs off of PCIe 4x. Some motherboards and drives use PCIe 2.0, while some others use PCIe 3.0.

 

The cheaper M.2 drives use PCIe 2.0 4x (but, this does not mean you cannot use the drive in a PCIe 3.0 M.2 slot! Keep this in mind, it's backwards compatible)

The Intel Z97 Chipset can supply up to 8 PCIe 2.0 lanes by default. So this would mean: The drive (whether is is 2.0 or 3.0) will be limited to PCIe 2.0 4x speeds (which is still DAMN fast)

 

Some motherboard M.2 slots and M.2 drives are PCIe 3.0 4x. This means you can get potentially higher speeds with these boards/drives.

Any combination will work! Check the rated speeds and interface of the drive. Kingston has a M.2 drive that achieves 1400MB/s in a 2.0 4x slot (yeah, pretty quick for PCIe 2.0), anything slower than that even if it's a PCIe 3.0 drive, it won't have any significant speed reduction.

 

Basically, your GPU will have ZERO performance loss from the M.2 drive, as M.2 runs off of the chipset's PCIe lanes, and the GPU uses the CPU's PCIe lanes.

You got nothing to worry about

[Sakkura]

 

M.2 runs off of PCIe 4x. Some motherboards and drives use PCIe 2.0, while some others use PCIe 3.0.

 

No, that's not true. M.2 can run at either 2x PCIe or 4x PCIe. The B notch on M.2 denotes a 2x PCIe connection, while the M notch denotes 4x PCIe. Those are the two most commonly used notches.

 

I would say 2x PCIe is more common than 4x PCIe at the moment, but over time that may change.

[TheZuluWarrior]

 

Righto haha. I'm gonna try to make this a simple as possible haha. I'll highlight the important, keep in mind, parts in bold.

M.2 runs off of PCIe 4x. Some motherboards and drives use PCIe 2.0, while some others use PCIe 3.0.

 

The cheaper M.2 drives use PCIe 2.0 4x (but, this does not mean you cannot use the drive in a PCIe 3.0 M.2 slot! Keep this in mind, it's backwards compatible)

The Intel Z97 Chipset can supply up to 8 PCIe 2.0 lanes by default. So this would mean: The drive (whether is is 2.0 or 3.0) will be limited to PCIe 2.0 4x speeds (which is still DAMN fast)

 

Some motherboard M.2 slots and M.2 drives are PCIe 3.0 4x. This means you can get potentially higher speeds with these boards/drives.

Any combination will work! Check the rated speeds and interface of the drive. Kingston has a M.2 drive that achieves 1400MB/s in a 2.0 4x slot (yeah, pretty quick for PCIe 2.0), anything slower than that even if it's a PCIe 3.0 drive, it won't have any significant speed reduction.

 

Basically, your GPU will have ZERO performance loss from the M.2 drive, as M.2 runs off of the chipset's PCIe lanes, and the GPU uses the CPU's PCIe lanes.

You got nothing to worry about

HUZZAR! i understand! lol 

so i can use my gtx 980 at pci-e 3.0 x16, and have a ssd in the m.2 slot running off x4 pci-e 2.0. 

so all i really need is to find the ssd i want to stick in the m.2 slot and im good to go. 

but this is all dependent on if i can find a ssd for a decent price that will preform better then a normal sata 6gb/s drive. 

OR! do you think i would be better off waiting for sata express drives to be available? as they will run at 10gb/s just like a m.2 ssd will likely do?

open question right there, someone hook me up with some advice on that one

ps. what i have so far is http://uk.pcpartpicker.com/p/KZTBt6

[Sakkura]

so all i really need is to find the ssd i want to stick in the m.2 slot and im good to go. 

but this is all dependent on if i can find a ssd for a decent price that will preform better then a normal sata 6gb/s drive. 

OR! do you think i would be better off waiting for sata express drives to be available? as they will run at 10gb/s just like a m.2 ssd will likely do?

open question right there, someone hook me up with some advice on that one

 

Right, finding the SSD is the main issue. M.2 is backwards compatible with SATA, so there are plenty of M.2 SSDs that are just SATA drives with the new connector, so they'll perform exactly like regular SATA SSDs. The M.2 SSDs that can take advantage of the extra PCIe bandwidth tend to be more expensive, and many of them aren't even that fast in real-life testing - they may show high sequential transfer speeds with the new interface, but random IO performance isn't always up to scratch. A fast SATA SSD like the Samsung 850 Pro can beat more than a few PCIe-based M.2 SSDs in that area, which leads to better overall real-life performance because random IO is more often going to make a noticeable difference than sequential IO (even HDDs have pretty decent sequential IO speeds).

 

The M.2 slot on the Asus Z97-A motherboard runs PCIe 2.0 x2 only - so the theoretical maximum speed is 1 GB/s, vs. the theoretical maximum of 600 MB/s on SATA3 (AKA SATA-600). Realistically, SATA3 SSDs hit the wall around 550-560 MB/s, so presumably PCIe 2.0 x2 M.2 SSDs would similarly hit a wall around 900 MB/s. But the market hasn't really matured yet, there are a few M.2 SSDs that can run way faster than even that (like the Samsung SM951, a PCIe 3.0 x4 SSD that can hit 1.7 GB/s if the port allows), and some that only go a bit past the limit of SATA3 (like the Plextor M6e that breaks 750 MB/s on a good day).

 

The future of SATA Express is uncertain. In part because M.2 works for both laptops and desktops, while SATA Express is desktop-only, and in part because SATA Express is limited to 2 PCIe lanes. M.2 can scale to 4 lanes.

[TheZuluWarrior]

Right, finding the SSD is the main issue. M.2 is backwards compatible with SATA, so there are plenty of M.2 SSDs that are just SATA drives with the new connector, so they'll perform exactly like regular SATA SSDs. The M.2 SSDs that can take advantage of the extra PCIe bandwidth tend to be more expensive, and many of them aren't even that fast in real-life testing - they may show high sequential transfer speeds with the new interface, but random IO performance isn't always up to scratch. A fast SATA SSD like the Samsung 850 Pro can beat more than a few PCIe-based M.2 SSDs in that area, which leads to better overall real-life performance because random IO is more often going to make a noticeable difference than sequential IO (even HDDs have pretty decent sequential IO speeds).

 

The M.2 slot on the Asus Z97-A motherboard runs PCIe 2.0 x2 only - so the theoretical maximum speed is 1 GB/s, vs. the theoretical maximum of 600 MB/s on SATA3 (AKA SATA-600). Realistically, SATA3 SSDs hit the wall around 550-560 MB/s, so presumably PCIe 2.0 x2 M.2 SSDs would similarly hit a wall around 900 MB/s. But the market hasn't really matured yet, there are a few M.2 SSDs that can run way faster than even that (like the Samsung SM951, a PCIe 3.0 x4 SSD that can hit 1.7 GB/s if the port allows), and some that only go a bit past the limit of SATA3 (like the Plextor M6e that breaks 750 MB/s on a good day).

 

The future of SATA Express is uncertain. In part because M.2 works for both laptops and desktops, while SATA Express is desktop-only, and in part because SATA Express is limited to 2 PCIe lanes. M.2 can scale to 4 lanes.

Ok.

so basically for now, save myself the headache and get a sata ssd, and maybe add something else in the m.2 slot in the future.

i can also get a far better sata ssd for the money of a m.2 ssd.