RAM not working?!

Apr 2, 2018
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I just changed my thermal paste on my pc and i clean the motherboard with compressed air.
Now only two out of my four RAM docks works. Is it possible i damaged some components with the compressed air? Why is this happening??? When i put in all four ram sticks the pc doesnt even boot into bios, it just turns on and off, on and off. It only work it I put in the RAM in solts 2 & 4 . any RAM into slots 1 & 3 makes the pc not want to boot.
All RAM is the same. G Skill 4gb sticks. They all worked perfected until now.
Tried clearing CMOS, but nothing changed. Im so confused.
Any Suggestions? Please Help!

Motherboard is GIGABYTE Z68XP-UD4