Is this problem with my motherboard or graphics card

Hello Friends,
I (6 years back) bought a motherboard
msi 790fxgd70 and processor amd phenom 2 x4 925
corsiar VX550. And sapphire at radon 2 gb graphics card..2 gb corsair ddr3 ram

From today suddenly my cpu start but no monitor display although cpu fan and lights were running.. No power on keyboard either.. I thought it was problem with monitor or keyword so I tried to unplug both with mouse and use it on my another old pc..but to my surprise it ran although that is just a showpiece as. It had really low configuration.. But my mouse was not working in that too

I called my hardware engineer he said it could be display problem from motherboard but I didn't discuss about graphics card with him

So my query is what you think could be the issue and how I know that my mother board is gone or graphics card or both

At a preliminary level, try the following
1. Re-seat the RAM
2. Try RAM in another slot
3. Clean the RAM slots using a light brush or if you have IPA cleaner spray the same on to the RAM slots
4. If you have a speaker attached to mobo, then try with just CPU and nothing else, no RAM, no GFX and see if it gives any series of or long beeps

sorry that didn't work.. and hardware engineer told me to get new board and processor