PC turns on. Fans working. Black Screen No signal NO BEEP.

Tried resitting the RAM. Tried without RAM or just 1 stick.

A 10-11 year old machine.
Windows 10 Home 64 bit
EVGA 780i SLI Motherboard
ntel Core2 Extreme X9650 CPU
4GB of OCZ DDR2 RAM (2 sticks)
Asus 670 GTX DC2T
Silencer 750 EPS12V PSU 80PLUS
Corsair RGB K70 Mechnical Keyboard.
Logitech G500 mouse

I need help guys.
Screen is black, and motherboard doesn't beep.
It won't even beep when I disconnect almost everything except the power supply.

Thank you for your quick response and help!
First, I think I had beeps before.
Can you please explain Step 1 again. I have 3 pin and a plastic jumper of 2 (pins).
Here's a close up image (it's blue 3 pin plug).

What exactly do I need to do and how?
Tried removing the battery for 5 minute. Didn't work. Strangely the screen is black, like it's on standby, but there's no "no signal" or anything.

As for step 2: I don't have an on-board GPU, however I've already tried 3 different GPUS and nothing worked.

I had an old-school technician coming here. He tried to replace the PSU, also tried a simple Geforce 200 GPU - black screen, no beep. He tried unplugging everything including the SATA and RAM - and there was absolutely no beeping.

Yeah, well there has been some issues for quite some time now, but until today I wasn't really able to pinpoint them.
The main issue was the pc locking-up and freezing-screen turning black and then crashes after a while or I would have to do manual reset. Basically the PC would freeze-blackscreen and crash randomly and without warning.

I think I had similar issue to this one before, but stuff like unplugging -replugging main power cable, messing with the battery, or with the motherboard power, or even the gpu and stuff - would fix it eventually. Nothing like this when nothing I try seem to work.

The PC (excluding GPU) is over 11 years old I believe. So RMA isn't an option and I don't know anyone who can repair the motherboard, I doubt there is.

There's no onboard display port unfortunately. But I did try GTX670, GTX 980 and a basic geforce 200 or something that technician gave me. He believes it's a dead motherboard.
The fans of the case, mobo and gpu are definitely spinning, they are not going on and off.

I still wonder if some electric discharge or reset of mobo will work....

Oh one more thing. If I end up buying a motherboard or a new pc- what happens with the Windows 10 (formerly Windows 7) llicense?
Can I transfer my current windows 10 account ( KEY license) from 1 motherboard to the next?
What about the system itself? Would I need to install Windows from scratch and or format? Providing the HDD is fine.

P.S- while we do know the old mobo is at fault here- we don't really know if the other components are fine- but everything points out that they are.
If there is anything else I can attempt let me know please.

Honestly I am still open to any and all suggestions.
Thanks forall the help and advice.
Windows license thing kinda worries me though, it would be nice to have a positive answe. Last thing i want is to spend more time in an ancient dying machine. So buying a windows license would be really bad.
Yeah this pc is OLD It used to be my gaming PC back in the old days when Elder Scrolls IV Oblivion and Cryisis came out about 10-11 years ago. But it was converted to my main browsing and work pc.and secondary small gaming for LAN-like coop or lighter games.
And the PC actually worked quite fine and fast even - minus the freezing.
But this is a huge wall collision for me.
I thought about buying a old motherboard that support the 775 socket:
https://m.ivory.co.il/catalog.php?id=6575
This is such a basic model though, only 1 PCI E X16 etc. About 127 $ here in Israel.
There's also a guy on Ebay who sells a 780i SLI Asus Striker. Which seems to be just like my motherboard basically. He sells this for 100$ +70$ shipping. Plus potential tax here in Israel.

Again- if there's a way to get this old boy back in order without spending serious money on it I'd go for it.

Thing is, I have a solid strong Gaming PC based on i5-3570K that is well able to run games at 4K@60fps or 1440p@144MHz with an Asus 1080 Ti Strix OC GPU.
I recently upgraded from a 980 SLI on my main gaming PC - to that 1080 Ti. I decided it's too early for me to build a new pc now. I rather have this gaming pc rocking for as long as I can, and upgrade in the future when the tech leap would be bigger and upgrade more significant and impactful. Besides it's expensive and mentally& time consuming & demanding to research, purchase and assemble a new high end gaming PC from scratch. And I don't feel like spending that kind of money and time now.

My idea was to build a brand new gaming PC (and i've been postponing it) and then have my current beast of a gaming pc move to be my secondary work/gaming/browsing PC. That way I could also use it for some local 2-pc coop games at home, and of course for work.
I just didn't want to be forced to do this now when I am not ready and I don't find it necessary you see?
Buying the 1080Ti was suppose to be a ticket to lengthen my Gaming rig's lifespan and keep it competitive, capable and powerful.
Just wish my 'trusty' old work rig didn't die on me.
There must be a way!.......isn't there?

Still no success. Tried pretty much anything's possible. Motherboard is the prime suspect right now.

EDIT: Sent to a technician guy to examine the parts in a lab with software and test-benchmarks etc. Everything is OK except the Motherboard, as suspected. Technician claims it's a dead/bad North Bridge issue. Didn't care to elaborate. Said it cannot be fixed. Not sure how talented, skilled or ambitious he is.

Ideas???