Question i don't know what's wrong with my pc

[Lerrisc]

My mobo has 2 slots and i have two 4gb ddr3 ramsticks.my pc detects the two and uses it but sometimes it only detects 1 even if the two are connected and sometimes it detects the two which is 8gb but only 3.45 usable,i tested my ram by putting 1 stick at a time in the slots and all of them runs fine,im confused,i'm thinking also maybe its the cause of my pc crashing or shutting down randomly without warning.my pc is better than my friends pc because i also have a grphics card gtx 750 ti 2gb but my friend never expirience this,also one of my slots feels so hard/stiff maybe because i don't hear the click sound when i put my ram,there's no dirt or dust in it but it so hard to put my ram on it.hope you could help me

 

[Obakasama]

Full specs?

The two things could be coincidental. Depending on your specs you should double check which slots the RAM sticks are installed in. If memory serves they should be in A2 and B2 slots (an empty slot in between). Have you checked the latch at the end of the slot? The slot shouldn't be that stiff. For RAM issues you could use Memtest to diagnose.

The other thing is whether you've configured the PC, assuming Windows, for crash dumps to see whether there are any known causes.

EDIT: Ignore the slot thing mentioned, re-read your post and it states only two slots. Still consider Memtest to diagnose.