PCIe 2.0 x16 (x2 Bandwidth) what does that mean?

[Frazman2001]

as the title says i am wondering what PCIe 2.0 x16 (x2 Bandwidth) means, i have 2 pcie slots on my motherboard the top one being pcie 3 x16 and the second one being PCIe 2.0 x16 (x2 Bandwidth) i am thinking about putting my new graphics card here because their is more room there than there is in my top slot. Will it work?

 

[rgd1101]

it mean the slot can take a x16 wide card. but only run at x2 speed
no. don't put it only the second slot

 

[Frazman2001]

it mean the slot can take a x16 wide card. but only run at x2 speed

will that bottleneck a gtx 980?

 

[Rogue Leader]

You always want to run your GPU in the slot closest to the CPU. It will provide it the most PCIe lanes and performance. Now its not a huge difference, but its a 2-3% difference in performance. However if you must it will still work in the lower slot.

 

[rgd1101]

it mean the slot can take a x16 wide card. but only run at x2 speed

will that bottleneck a gtx 980?

what is the make and model of the motherboard?
if it really running at x2. it only about 8 times less than what it should be

 

[Frazman2001]

it mean the slot can take a x16 wide card. but only run at x2 speed

will that bottleneck a gtx 980?

what is the make and model of the motherboard?
if it really running at x2. it only about 8 times less than what it should be

its an ASUS Z-97p

 

[rgd1101]

it mean the slot can take a x16 wide card. but only run at x2 speed

will that bottleneck a gtx 980?

what is the make and model of the motherboard?
if it really running at x2. it only about 8 times less than what it should be

its an ASUS Z-97p

Not unless you want to waste your gtx 980. use the first slot closest to the cpu.

 

[lakimens]

Do not put your GPU in that slot.
It is running a lot slower than an x16 slot.
Now, I know that a GPU doesn't come close to filling the x16 speed, but I am pretty sure that slot will make your 980 act like a 740.

 

[Rogue Leader]

Reviewing the manual as well
http://dlcdnet.asus.com/pub/ASUS/mb/LGA1150/Z97-P/E9385_Z97-P.pdf?_ga=1.21663549.784991535.1466022091

It does say to not use the second slot except for a second card, just in case you wanted confirmation from ASUS directly.

I have never seen a slot that only runs at X2 but there it is, so even if it did work I wouldn't use it, it will bottleneck that card considerably.

 

[joex444]

what is the make and model of the motherboard?
if it really running at x2. it only about 8 times less than what it should be

The PCIe 2.0 x16 (x2 bandwidth) means the slot is physically x16 but electrically x2. Since this is PCIe 2.0 not PCIe 3.0 it is the same as a PCIe 3.0 x1 slot. This means it has 1/16th the bandwidth (except that PCIe 3.0 x1 isn't *exactly* PCIe 2.0 x2).

Technically 8 times less would mean it has negative bandwidth, right, if x16 is 15.75GB/s for PCIe 3.0 then 8 times less would be 126GB/s less or -110.25GB/s. Really this slot would have 1GB/s, so 1/15.75th which is very close to 1/16th (within 2%). A loss of 93.6% of the bandwidth.

OP: Your card should have 15.75GB/s of bandwidth. That other slot has 1GB/s of bandwidth. It's the same as a PCIe 1.0 x4 slot. This is enough to impact your gaming performance on the order of 5% in the worst case scenario. While it will work, the top slot is connected to your GPU and the bottom slot is connected to the chipset which is connected to the GPU. Using the bottom slot introduces this extra layer of communication and forces all of that PCIe data to be transferred via the link between the the CPU and the chipset which is shared with every other device in your PC -- all your SATA drives, all your USB devices. It could be far worse than simply a PCIe 3.0 x1 slot connected directly to the CPU, which is already enough to cause a 5% drop.

 

[k1114]

More than just 5%. https://www.techpowerup.com/reviews/NVIDIA/GTX_980_PCI-Express_Scaling/21.html Running off chipset lanes is not another 5%.