Something died,not sure if CPU or MoBo

[TuN]

My gear:

• Asus P6T Deluxe
• Intel i7 920
• Mushkin HP-580AP
• 2x 4GB Mushkin DDR3 2000Mhz
• 1x 4GB Corsair Vengeance DDR3 1600 Mhz
• Samsung SSD 830 128 GB
• Palit Jetstream GTX 770 2 GB

So,I have been using this computer for about 8 years and had pretty much no issues. But since last 2-3 weeks, computer sometimes didn't want to boot instantly, I had to put PSU to Off,and On,and then it booted. But today it didn't want to, so I have decided to replace the PSU with an old Enermax 500W that I had lying around,but the pc doesn't want to boot. It does turn on when I jumpstart it, but when plugged into motherboard, it doesn't power up. The mushkin also powers up motherboard but doesn't even jumpstart.
So it looks like there is dead PSU and Mobo,but kinda doesn't make sense for both of them to die at the same time.
Any ideas? Sadly don't have another LGA 1366 motherboard around.

 

[tinytomlogan]

If you changed the PSU and its the same, that kinda means its not the PSU?

Or am I mistaking what you wrote?

 

[TuN]

Well the psu that was in the computer since start, doesn't turn on when jumpstarted, that's what is confusing me.

Edit: if the old psu would jumpstart normally, I could be pretty sure that it is the mobo,but now it just seems weird