Right that tells me you have a good PSU which should be fine, everything spinning up confirms power is getting through, but of course this does not guarantee the PSU is good, easiest way to prove it is to use a
PSU tester, but in this case I doubt the PSU is at fault.
The fact you get no beeps with the ram removed is a pain, one hopes it's as simple as the board has no speaker, although I thought they all did these days, without these it makes it hard to know what the system is up to, unfortunately from what I can see the board does not appear to have an LCD poster display ? these are used in Lou of speakers on some boards like my board does.
So without being able to provoke beeps we are fighting a losing battle, the only ways round this are to get a speaker for the board, I have one I keep for such emergency's, took it from a dead system, it's a simple plug with the speaker on 2 wires, if you can't find such a thing then we need another system to swap parts about with to be able to prove whats good and bad, this also brings problems that you need a similar spec system when it comes to the ram, you can't put DDR3 ram in a DDR2 board, not unless it's one of the rare crossover boards that offers an either\or option.
But currently the video card is my suspect given your getting no display at all, so before we get too involved ion the other parts lets get that checked, you should be able to swap it into another system that works to see it it behaves or not, equally put a known working card into the problem system, if this gives a result you have your issue, as sure as we can be in this situation anyway, so see what this does for you and we can go from there.
You say you changed nothing recently, but did you clean out the dust bunnies perhaps ?
Just wondering about cable(s) becoming loose, so when swapping cards about as well as making sure they are seated properly, make sure the cables are secure, including the monitor cable, nothing worse than chasing ghosts when it';s a simple answer lol, also whats your electric like where you are ? I'm wondering if your prone to surges, and as such have you got any surge protector or anything to protect the system ? it's mad not to these days TBH, hope this helps a bit anyway.