Unnecessary Lagging During Gaming, Potential Bottleneck

[MetalSparks]

Hi, guys,

My previous system consisted of a CPU with 16 lanes, an MSI Golden GTX 980 Ti, a GTX 650 PhysX slave, and an M.2 x4 SSD. The M.2 requires 4 of 16 CPU lanes, which means that the only way the GPUs could work is by running in x4 mode instead of x8 mode, and I think that was the cause of the bottleneck.

1. Would running those GPUs in x4 instead of x8 cause a considerable bottleneck?

2. Would running the PhysX card on a PCIe 2.0 x16 lane instead of a 3.0 lane drop its lanes down to 4 so the 980 Ti can utilize a total of 8, or would I literally need a x16 to x4 riser card to force the PhysX card to run in x4?

3. Assuming the PSU is adequate would having a PhysX card in x4 hurt the system more than simply removing the card altogether?

 

[k1114]

Most mobos have 8 lanes of their own. You should check with yours since different mobos have different slots and also wire them differently.

1. 5% or so, it's not much. https://www.techpowerup.com/reviews/NVIDIA/GTX_980_PCI-Express_Scaling/21.html

2. Goes with what I said before, depends on your mobo. If you put it in a slot that uses the mobo 2.0 x4 slot than the 3.0 x16 from the cpu is all for your gpu. That's assuming the m.2 isn't interfering.

3. No the physx card would not be affected running at x4 and that benefits any physx games.

 

[MetalSparks]

That doesn't make much sense.

I have an ASRock Z97 Extreme6, so it has an M.2 x4 (3.0 x4,) 2 PCIe 3.0 x16, and 1 PCIe 2.0 x16, so there are a total 52 motherboard lanes, but the CPU would be limited because it only supports a total of 16.

I find it hard to believe that a 3-5% performance would cause a lagspike of 20+ fps on 1440p Ultra AAx4 PhysX medium, especially if there's a dedicated PhysX card.

The CPU is also an i7-4790k at 4.2Ghz 1.888v, so it's not a CPU bottleneck.

HDD is a 1TB 3.5" WD Blue 7200RPM, and both the SSD HDD have more than half their capacity left, so no drive issues.

RAM is 2x8GB 2400Mhz CL13, so no issues there.

PSU is an 850W Corsair 80+ Gold.

Temperatures are always below 50C.

Is there any other reason why I'm having random lag spikes?

 

[k1114]

If you read the manual, you'll see which slots are shared. So if a certain slot is occupied, it lowers or disables another. You don't just count slots and say how many there are. That's not how it works but don't forget pcie x1 and mpcie also use lanes. You've got a total of 24 to use. Not 16.

Pcie bandwidth isn't the cause of your performance issue.

If your cpu was at 1.888v it would be instakilled. Check usage and temps of everything. Usage of cpu per core.

 

[MetalSparks]

If you read the manual, you'll see which slots are shared. So if a certain slot is occupied, it lowers or disables another. You don't just count slots and say how many there are. That's not how it works but don't forget pcie x1 and mpcie also use lanes. You've got a total of 24 to use. Not 16.

Pcie bandwidth isn't the cause of your performance issue.

If your cpu was at 1.888v it would be instakilled. Check usage and temps of everything. Usage of cpu per core.

My PCIe don't share lanes with the M.2 x4. There's an M.2 x2 that will share lanes with 2 Sata Ports, but the M.2 x4 is dedicated.

1.888v VCCIN, not vCore.

Temps at 100% CPU load don't pass 62C.
Temps at 100% GPU load don't pass 75C.

 

[k1114]

The m.2 that is x4 does share from the 16 from your cpu. You can even go look in gpuz and see what your gpu is running at. http://www.asrock.com/mb/Intel/Z97%20Extreme6/?cat=Specifications

- 1 x Ultra M.2 Socket (M2_1), supports M.2 PCI Express module up to Gen3 x4 (32 Gb/s)
- 1 x M.2_SSD (NGFF) Socket 3 (M2_2), supports M.2 SATA3 6.0 Gb/s module and M.2 PCI Express module up to Gen2 x2 (10 Gb/s)

*If M2_1 slot is occupied, PCIE2 slot will run at x8 mode, and PCIE4 slot will run at x4 mode.
** The M.2 Socket (M2_2), SATA3_4, SATA3_5 and SATA Express share lanes. If either one of them is in use, the others will be disabled.

Still the bandwidth isn't the issue. The only missing info is usage during the lagspikes. That will get what's causing it, hopefully.

 

[MetalSparks]

Ah, so lanes are actually pulled from PCIe with M2_1 installed; the PhysX card must be running at x4.

I checked usage, but I barely reach 70%, but the PhysX card may be causing issues when rendering is set to "high." Changing it to "low" fixed the lagspike. ...disappointing, as you'd think games could be coded more efficiently.

Thanks for the help!