Re: Inexplicable hitching in all games.
Are you monitoring temps?
What you're experiencing is what reviewers will call the '0.1% Low' framerate. Essentially, if you're pulling a fairly consistent say, 100fps, and for one or two frame loads the rate drops to say, 40fps, you'll notice a big stutter, before it returns to 100fps and feels smooth again.
This is usually symptomatic of some kind of bottleneck. I used to get this behavior when trying to game with a game installed on a WD Green low-RPM disk. There isn't really any writing going on between disks when you game, so it's not that, and your SSD and WD laptop drive are going to be faster than my low power low RPM archive drive.
I'd do the following:-
1. Update ALL system drivers if updates are available. GPU drivers, Chipset, BIOS/Microcode if one has been released for your device (be VERY careful with BIOS though, read the manufacturers instructions and don't skip versions), SATA or storage controller, the lot. any of them could be causing hitching. Sometimes you might see errors in eventvwr if your sata drivers are causing ATAPI errors.
2. Monitor temps. Are they spiking, is something throttling? Manufacturing doesn't always go smoothly. My friend once bought an MSI gaming laptop and we quickly realised that the cpu heat sink mounting was loose on one side, causing massive throttling!
EVGA SLI Micro Z68 // Intel i5-2500k @ 4.4GHz // 8GB Corsair Vengeance 1866MHz // Overclocked ASUS GTX 660 Ti // Corsair Carbide SPEC-03 // Kingston Hyper-X 120GB // 2TB WD Green + 500GB WD Black