PC booting into 'slow mode'

Hi Guys,

Got a bit of a weird problem with my computer. If I boot it up sometimes it takes an age (15-20secs) to get to the Gigabyte splash screen. After than when I'm in Windows the performance of the computer is way way down. On games it's literally a slide show and I'm getting 1fps in 3dMark where I used to get 100fps. If I reboot the machine it's fine, back to normal with full performance. To make things worse sometimes the machine just works the first time, usually it will not but sometimes it will. It's a real intermittent problem.

I'm guessing it's something early on that's causing the problem due to the Gigabyte splash screen taking an age to load up, during this time the PC is powered on but the screen is black.

This was happening before I overclocked so I don't think it's related to that.

Specs are:

i7 4770k @ 4.2GHz
Gigabyte Z87X-D3H runing F7 BIOS
K2 Mount Doom Cooler
8GB G.Skill
2x HIS 7950 ICEQ @ 1100/1400
850W XFX PSU
OCZ 120GB SSD
1TB HDD
Xonar U7

I've uploaded a quick video of what it's like in 'slow mode' in the BIOS:

Anyone have any idea what it may be?

I assume you have re-installed your graphics driver?
Does it do the same with a single card?

If you've got onboard I'd remove both your gfx cards and test it, then if that's ok put one in and repeat.

I was having a very similar problem with my Z77 based pc and I'm not sure what actually fixed it, I did a bios update and a clean install of the video drivers and it was ok for a bit, then I kept losing one graphics card on boot then did another clean install of drivers and its been perfect ever since.

In windows do you find minimising things etc happens in slow motion?