PCIE Lanes question

[Phrozyn]

System Specs

i7 4790k

MSI 780ti

MSI z97 Gaming 7 Mobo

750w PSU

250 SSD + 3TB HDD

Windows 7

Custom Water cooled loop

 

I made a post awhile back mentioning that my FPS feels lower than it should when it's under stress, but FPS counters still said 60+. So after browsing around and reading various things, I read that the hashwell CPUs only allow up to 16 PCIE Lanes, which would mean my sound card that was running at x1 was making my GPU run at x8? So as of recently, I took out my soundcard and it looks like my FPS issues are all gone!

 

So now I am curious.... can someone explain how PCIE Lanes work? I read that that the CPU that I have has access to 16 lanes, but the chipset itself has access to 22, so is it possible to have my soundcard and my GPU running at 16 lanes?

 

Thanks in advance!

[TheGeekster]

While gpu's have access to the 16x lanes, 99% of the time they don't ever need that much bandwidth, especially with pcie 3.0. You'd only notice an issue if you were trying to run the 780ti on a 4x slot.

 

Having the soundcard running at the same time shouldn't affect the graphics card. If the FPS counters say above 60, then it's gotta be above 60. It could possibly be a compatibility issue between the sound card and the game? 

 

(Pcie 3.0 is double the speed of pcie 2.0, so a 8x 3.0 slot is the same bandwidth as a 16x 2.0 slot)

[Glenwing]

Most x1 slots are wired to the chipset, so they won't use any of the 16 primary lanes provided by the CPU.

CPU provides 16 PCIe 3.0 lanes, these are usually used for the full length x16 slots. Chipset has 8 PCIe 2.0 lanes, used for x1 slots and various I/O controllers like third party USB 3.0 and SATA controllers if your motherboard has any.

[AlwaysFSX]

Think of it like lanes on a road, the more you have the more cars you can have traveling together at once.

[Phrozyn]

So I was messing around and I apparently had my 2nd monitor using the integrated graphics, so I switched it to my GPU and... it looks like my weird FPS issue has come back...

 

When my 2nd monitor has chrome open or a video running, my game has that weird FPS issue. (Where my FPS will be 100, but look like 10 FPS.. if I minimize or close everything on the 2nd monitor FPS looks normal yet it didn't actually changed and was still at 100)

 

So... 

If using GPU for both monitors, no soundcard, lame FPS issues

if using GPU for one, Integrated for 2nd monitor, no soundcard, good FPS

If using GPU for one, Integrated for 2nd monitor, with soundcard, lame FPS issues

 

So why does it feel like my GPU is choking on some type of bandwidth issue?