I've recently built a new system with these components:

Asus Rampage V - Intel i7 5960X @ 4.3 GHz - 16 GB Corsair DDR4 2800
2x EVGA GTX 980 SC (SLI) @ 1514 / 3900 MHz
Silverstone Fortress FT02 - Thermaltake Toughpower DPS G 1050
aquaduct 720 XT mark V - Aqua Computer cuplex kryos HF - EK Waterblocks EK-FC980 Nickel

I have a couple of problems which might be caused by the motherboard (using BIOS Version 0705).

The most serious and curious problem is that some games show an irregular and heavy stuttering, especially when moving around. Affected is Shadow of Mordor and Bioshock: Infinite among others. Some games work fine though. The problem exists in Windows 8.1 only! I reinstalled Win 8.1 completely, but the problem persists. In Windows 7, though, the games run perfectly smooth, so I'm pretty sure that the hardware itself works fine.

I've tried everything, like reverting to BIOS defaults (i.e. no OC), disabling SLI, reinstalling Win 8.1... no effect. The problem persists. Something with the different RTC routines in Win 8.1 perhaps?


Second problem: The USB 3 connections are unstable. Especially when using USB 3 hubs. I get error messages saying that the system resources are insufficient when I connect certain devices. It cannot be related to the USB power supply, though, since the USB hubs are all powered and the same setup worked just fine on my old system.
Also, the Logitech G19 keyboard often fails to be initialized correctly when attached to an USB 3 connector. It works just fine on the "KeyBot" connector, though, however the keyboard fails to work at all, if the KeyBot is turned on (which I don't really mind, though, since I don't need that feature anyway).


Third problem: The board is unstable during boot. Like some other people here have written, it sometimes fails to boot at all showing various error codes. After a power cycle, it usually works fine. But a more serious problem seems to be connected to the USB hand off procedure. The boot of the OS is failing sometimes when the board is doing its USB hand off to the OS. At least that's what I assume, since the OS boot is hanging when the USB devices (keyboard) are usually initializing and if I turn off the USB hand off in the BIOS settings, this crash never seems to happen - for the tradeoff that I cannot use the keyboard for the Windows Boot menu, which I need.


And finally a question:

I've connected the 8 pin power connector top of the CPU and the molex connector at the bottom. But I couldn't connect the additional 4 pin power connector at the top, because my power supply just doesn't have an additional connector for that.
Could that be the cause of some of my problems?

Thanks & regards!