My poor self need help.

[Prunes]

Is really my GPU dead? this will be long bear with me.
So after i though my gpu is dead i bought an sale 
Rx 480, my old card is Rx 460
And my new card acting the same.

So when i open my Computer there's a chance it won't boot
and the debug led turn on VGA. Then went out.
Sometimes ill wait it out and boots.
Sometimes it doesn't. Even restaring cause no signal
My onboard works so it's okay.
I already replace my old PSU.
Which is Seasonic 520w from Corsair VS550w.
Replaced my Broken ram.
Is it possible a Motherboard?

Cause really backthen i was cleaning my PC.
My motherboard Smoked like something was burnt.
But still works so i didnt mind it.
now i think i might be the root of my problem.

My full Specs :

 

I5- 6500 
Msi inightelf b150

4x2 Ddr4 2166 HyperXfury

Seasonic 520w
1 Fan 120mm

Intel SSD 120gb
1tb HDD
Rx 480 4gb.

I'm sorry for being noob.
I'm new here.
Sorry for bad English.
 

[Bombastinator]

Rule #1 of computing: never let the blue smoke out.

[Whiro]

2 hours ago, Prunes said:

Cause really backthen i was cleaning my PC.
My motherboard Smoked like something was burnt.

that’s never a good sign tbh

Did you tried your gpu in other pcie slot?

[Prunes]

I tried the other slot and still do the same.
problem is it's so hard to find another board.
 

[Whiro]

48 minutes ago, Prunes said:

I tried the other slot and still do the same.
problem is it's so hard to find another board.
 

Well in that case I would start with typical troubleshooting methods.

Clear cmos. 

You can reset the UEFI settings (clear CMOS) by one of the following methods:

 1. Go to the Exit tab in the UEFI and select Load Optimized Defaults.

2. Press the Clear CMOS button on your motherboard (if it has one).

3. Unplug the computer and remove the coin cell battery on the motherboard for a few minutes and then reinsert it
Next try DDU all drivers in safe mode and reinstall new ones straight from AMD website. 
Make sure windows is up to date.

Last not least if any of that not helps install fresh copy of windows. 
If any of the above not gonna work next will be testing your gpu in another system (if possible, as some friends maybe)