[Resolved] 1 second stutter all of a sudden

[Safecandy]

Fallout 4 has been running perfectly at 45+ FPS using near-ultra settings for months (hundreds and hundreds of hours) on my rig until about a week ago when my game started experiencing a very regular lag spike for about 1-2 seconds every 60 seconds after loading up a save (does not do this in the start menu).

I opened up my task manager and saw Fallout.exe was dipping in CPU utilization from about 70% down to about 30%. Looking at HWMonitor, indeed all 4 cores are dipping in utilization every 60 seconds except when the game is paused, then only core0 shows a dip down to about 30%. Processor powers dip too, but I can't tell if that's the cause or that they dip because CPU utilization from the game goes down.

In-game settings and mods are not the problem. The issue persists with the lowest settings selected and no mods loaded. I started a new game and it happens in the prologue as well. I even uninstalled/reinstalled the game and the issue persists.

Temp is not the problem. Fans are all running and mobo temps are steady in the 30's. The 4 cores of my i5 4690 show healthy temps with the game running (50-60 C or so) the CPU at 60-70% and idle in the 30 C range. Besides, CPU throttling is disabled in my BIOS. Even under Prime95 torture testing the temps stayed in the low 80's. The CPU cores did not dip below 100% during the torture test (though I only ran it for 30 min or so), making me think my hardware is probably fine.

No other processes are spiking CPU usage during these dips, no memory spikes, no disk writes either. I noticed ethernet activity was sometimes coinciding, but it was from Windows' system process, not a 3rd party program.

I'm running Windows 10 and have been since Jan shortly after starting to play FO4 and the only thing left I can think of that might be at work here is that Windows updated itself last week around the same time I started having this issue. It was a security update for Windows (KB3172985) and about 30 updates for Office 2007. Uninstalling KB3172985 didn't help (and Windows re-installed it automatically a day or so later).

I'm completely baffled at this point and any insight would be helpful!

**TL;DR**
Started middle of last week
Lag for 1 second every 60 seconds coinciding with CPU utilization dip from Fallout.exe
Happens whether paused or playing
Happens with new game or saved games
Does not happen in start menu or splash menu
Does not happen during opening cinematic
No other Windows or 3rd party processes are spiking at time of lag
No memory dip during lag
No GPU changes/problems
No temp problems

My system (Home Build):
Windows 10 Version 1511 for x64
ASRock H87M-ITX mobo
Core i5 4690 processor
game is installed on Intel SSD
GTX 950 GPU

 

[Safecandy]

I resolved the problem today, but not in the most elegant way.

I ran Prime95 *and* Fallout 4. My CPU cores all stayed at 100% while the Fallout.exe file dipped at its usual 60 second interval. I then downloaded and ran Fallout 3 and ran it at it's highest settings. CPU cores stayed at about 40% and didn't dip after letting it sit for 5 minutes and I didn't get any FPS drops playing for an hour (forgot how fun that game was!).

So, I decided Fallout.exe was F'd up for some reason or another and uninstalled Fallout 4 and deleted all of the local files (i skipped this step the first time I uninstalled FO4). Re-downloaded and installed and voila, consistent FPS in the 60s on near-ultra settings again.

So, I ended up using a tactical nuclear option (the thermonuclear option being wiping my C drive and installing Windows again), but my saves are all fine and my mods are running swell.