I have identified stuttering on two PCs caused by specific Windows updates
I posted this on Battlelog a year ago and have received no support, so I thought I'd post it here.
Summary of the problem:
-A Windows 7 update between KB2758857 and KB2939576 (this is as far as I can narrow it down) is causing significant stuttering on two different PCs, mine and my friend's.
-This basically translates to us not being able to install SP1 if we want to enjoy Battlefield 4.
-This manifests as sudden unprovoked drops to around 40fps several times a minute that severely interfere with aiming and flying on my PC, and a persistent drop to around 40fps for him.
-This issue is present on ALL driver versions. This issue is present both in Mantle and DX11 and at all settings from Low to Ultra.
-I have confirmed on both PCs that this issue is not present if updates KB2758857 to KB2939576 are uninstalled.
Specs:
-We have similar PCs with the only major difference being the GPU.
-AMD FX-8350 (stock clocks)
-Gigabyte 990FX-UD3
-16Gb of Corsair DDR3 RAM at 1600MHz
-I use a Samsung 840 EVO SSD and he uses a Seagate Barracuda 7200RPM HDD for Battlefield
-I use a Sapphire AMD R9 270X overclocked to 1130Mhz, he uses a Gigabyte AMD 280X at stock clocks
-Temps are all fine
Steps we have taken to resolve the issue before we identified it as Windows updates:
-tweaking in-game settings
-updating/downgrading GPU drivers
-updating motherboard BIOS
-installing more RAM
-clean Windows install
-RMA of 280X that we thought might have power issues (it did not)
How we came to this conclusion:
I had been helping a friend who recently built a computer, he had issues with his graphics card and BF4, we tried everything, RMA, reinstalled drivers, the whole nine yards, long story short we couldn't figure it out. He was always getting about 40fps with a 280X in both low and ultra settings.
Our last resort was to reinstall Windows, which fixed the problem, he was getting solid 60fps just as expected on that card.
However, after he installed some Windows updates, it went back down to 40fps.
We uninstalled the most recent updates, and left the ones alone that he had installed before the problem came back.
I was also having some unusual drops to around 40fps that I couldn't figure out, so I decided to try uninstalling those updates too.
It turns out that uninstalling these updates fixed the problem for both of us, we now both get 60fps in Ultra with no unusual drops, on his Gigabyte 280X and my Sapphire 270X respectively.
Of course this is not a solution as not being able to install SP1 means we can't enjoy some games that require it, for example my renewed interest in this problem is because I can't play both XCOM 2 and Battlefield 4 because XCOM requires SP1 to run.
I have further narrowed down the issue!
After a lot of searching I have identified the specific cause of the stuttering, which is improper core parking.
Upon inspection three of my eight CPU cores were parked while playing Battlefield 4, and I confirmed that my friend was experiencing the same issue.
We both use AMD FX8350 CPUs, and in both cases our cores were being improperly parked during gameplay resulting in abrupt, unprovoked FPS drops.
It appears that in one of the Windows 7 updates between KB2758857 and KB2939576, the way Windows decides when and which cores to park, or perhaps how Windows communicates with applications was changed, resulting in Windows being unable to communicate properly with BF4.
The fix for the problem was very simple and involved downloading a third party application that disables Windows core parking.
The result is Battlefield 4 running perfectly again!
I have been unable to narrow down which of the updates specifically caused this issue, but if in any of those updates between KB2758857 and KB2939576 changes were made to the core parking algorithm Windows uses, that would be the culprit. It should be pretty trivial to patch in order to prevent this problem from happening to other people, or indeed if the same problem might be present in the upcoming Battlefield 1.
I can provide more detailed system and driver information if necessary.
