More than on stick of ram, computer won't fully start

Caleb Miller

Reputable
May 10, 2015
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4,510
So I have a computer I built with,

-Intel core i7 860
-Windows 7 pro
-Intel ssd
-Corsair cx600
-MSI gtx 650
Cooler master hyper t4
-Intel DP55WG
Memory:
-(4x) 4 gb hynix 2Rx8 PC3 240 DIMM
-(2x) 2 gb MTB 1Rx8 PC3 240 DIMM (hp)

They all work, however my computer will only boot normally with one stick in, I've tried every combination possible, sometimes it turns on for a second then off immediately and tries again and again, or sometimes beeps with error code 21 (but all memory is tested and works). Could anyone please help or tell me my problem.