Really weird behaviour in Doom and Shadow of Mordor with Dual X5660s

[Pyroven]

The problem is very simple to describe; Completely randomly, in DOOM 2016 my framerate completely tanks for no reason.

 

In Shadow of Mordor, my framerate is never perfect but seems to have the same root spontaneous performance tanking.

 

In particular with Doom, the rest of the system slows right down as well, stuff like window animations are really slow. This makes me suspect it's something to do with the GPU, but I had this graphics card in an FX-6350 system before this and never experienced this issue.

 

The only things which stick out to me as perhaps problematic would be: the PCIE x8 slot the card is now in; the two CPUs perhaps communicating with each other.

 

But then again, the card shouldn't be bottlenecked by a PCIE 2.0 x8 slot and the CPUs shouldn't really cause any issue because I've seen youtube videos of other peole with similar systems playing Shadow of War just fine, and other games such as GTAV which are equally intensive have no issues.

 

 

I'm completely lost here. I also haven't been able to find any forum posts about anything like this.

 

 

Here are my system specs:

OS: Windows7 Ultimate

CPU: Dual Xeon X5660 @2.9GHz

Mobo: Tyan S7012

GPU: R9 280

RAM: 16GB Single channel (2x8GB, one stick to each CPU)

SSD: 240GB V300 (Boot drive, the game isn't stored here)

HDD: 2TB WD Blue 5200rpm, SATA 2 connected (The game is stored here)

Sound: USB 2.0 external sound card

PSU: EVGA 850 G2

 

***THINGS I HAVE RULED OUT***

 

-Nothing to do with Hyperthreading; Persists when on or off

-GPU + CPU temps are good (No thermal throttling)

-GPU VRAM usage is fine

-RAM usage is fine

-CPU usage is fine - Even single thread usage is fine; no one thread is very highly used. It's not a CPU bottleneck.

 

 

One final thing is that it does remind me of a VRAM bottleneck, it feels like one the way it goes from 60+ fps and perfectly fluid and playable to suddenly choking down to an unplayable ~10-15 fps (in DOOM). The difference however is that it doesn't happen necessarily when the scene gets more intensive.

 

In DOOM i've noticed it happens more often in the outdoor scenes, but in Shadow of Mordor it's comletely and truly spontaneous.

 

Any help would be greatly appreciated.

[Pyroven]

Solution: The GPU was being bottlenecked by the slot it was in. It was in the only PCIe 2.0 x4 slot and it was running through a different motherboard chip to all the others.

 

Moving it to another slot removed the bottleneck and the problems mentioned above.

 

 

 

 

EDIT: IT WAS ACTUALLY THE CHIPSET THERMAL THROTTLING.