Question 16.0 GB installed but only 7.95 usable

[JRF1910]

I've had this issue ever since I first assembled my PC. As the title suggests windows says I can use 7.95 of my RAM but I have 16 installed. Is there anyway to fix this or do I just have to live with it? I have gotten it to work by reseating my ram into slots 1 and 2 but it would blue screen my PC at random.

Solutions I've already tried:
Reseating RAM
Adjusting voltage and DRAM frequency
Adjusting maximum memory in BOOT Advanced Options

Specs:
Ryzen 7 1800x
B450 Tomahawk Max
Corsair Vengeance Pro 8x2
Gigabyte 1050ti
EVGA 450 bronze

 

[rgd1101]

so it won't work in the right memory slot?
test 1 stick in all 4 slot to see if any slot not working? or 1 stick is not working?

 

[JRF1910]

so it won't work in the right memory slot?
test 1 stick in all 4 slot to see if any slot not working? or 1 stick is not working?

I just finished testing this. So I always use the slots 2 and 4 as it suggests in the manual but my problem still occurs. I tried every slot with a single stick of ram, only slots 3 and 4 dont wont to boot up with a single stick of ram. The DRAM debug light, lights up when I try to. Does this mean my motherboard is damaged? Also yes, both of my ram sticks work.

 

[rgd1101]

check the cpu cooler. make sure it not too tight and warp the board

 

[JRF1910]

check the cpu cooler. make sure it not too tight and warp the board

I loosened them and still no change with slots 3 and 4

 

[rgd1101]

the other test is look for bend pin on the cpu. need to get new thermal paste.