Asus Z87-A: DRAM, CPU, VGA and BOOT DEVICE leds flash upon boot

I've replaced my case fan and moved some cables around to get a better airflow in my case. Now this happens upon boot:



1) Pc boots for a few seconds, then stops, then boots again, and this time boots into Windows just fine.



I've looked at the motherboard and I can see 4 LEDs light up and then turn off again one after another: DRAM, CPU, VGA, BOOT DEVICE.



I've gone through all cables, gently pushed down on both RAM sticks, gently pushed down on graphics card, booted without any fans connected, reset BIOS to default values, booted with different SSD - still the problem remains.



Isn't it strange? I mean: The pc ends up booting just fine, and then everything is normal, pc is 100% stable etc., in short: No problems what so ever. Except those LEDs that light up and then go out again at boot.



My system:

Core i7 4770 cpu

Asus Z87-A motherboard

MSI GFX 770 2 GB ram

16 GB Corsair ram

512 GB Crucial SSD

XFX 850W PSU

Noctua CPU fan

2 fans in front of cabinet, 1 in the back

Fractal Design R4 case



Thanks for reading, hope someone can help.



Best,

Henrik

Asus Z87-A: DRAM, CPU, VGA and BOOT DEVICE leds flash upon boot