Anyone willing to do some quick tech support?

How many ram slot do you have?

Propably memories are burned to ashes

If it's a pc you bought and didn't build yourself, 9/10 times it's the PSU. Try if you want booting with a friend's ram stick but still those things can't randomly break down :P

Get a memory stick from another computer (removing the others), plug it into your motherboard and try to boot.

http://www.downloadmoreram.com/

Specs. We need your system specs.

If I had to guess I'd bet it's a fried MB... But if you say that when you remove the RAM sticks the computer starts to boot and gives you beeping errors it might also be the RAM. Since the RAM is fried the CPU stalls but when you remove it you get the error (beeps) saying there is no RAM present.

Try to boot with new/loaned RAM first... If it still doesn't work it'll probably be the MB!

Look for burned (blackened) pins in your ram sticks. Also, when you tried them one at a time, did you put them all in the same slot?
Edit: read it now, you already tried it with no avail.

Have you turned it off and on?

Try posting your OP on Tom's Hardware.

Check your motherboard. Its the big thing, where all Ram and videocard and... is conected(in case you ask).
I had the same problem and one tiny thing on my motherboard was not properly connected, because it burned a bit...not realy burned, but it was a small burn 5*5 mm

Beeping Noise = RAM failure probably because in your 2nd test you removed the RAM. I'd say its your power supply if their is no fan noise on startup, however since the fans spin it contradicts your powersupply problem. You should do test with 1 graphics card, the only thing that failed on my 5 year old Dell XPS 630 was my nVIDIA GeForce 9800 GT.

My computer recently died too, everything would spin up for a second or two then turn off again.
Turns out it was the PSU, I could actually hear the capacitors hissing when it was turned on with the fans unplugged.

I would say mobo or cpu shot.

best approach I would take is to remove everything out and boot the system on outside of the case without any accessories attached. just 1 stick of ram and the hard drive. this is to eliminate any chance that it was from a static short. then you assess everything else that can go wrong into consideration.

Guess you have no choice but to buy a new pc?

It could be the PSU fault, if you can check its outputs for +5V and +12V with digital multimeter, you can be sure.
But from your description I'd say its motherboard's fault. Using RAM stick makes mobo to use more parts and one of them is short circuit, making PSU go to fail-safe state to prevent damage to anything else.

Try to fix it yourself, I'd look for fried elements around RAM slots, or search slots for possible short circuit or broken pins. If everything seems normal then you will have to buy another motherboard to replace failed one.
Not sure about status of CPU or RAM sticks, but chance they are fine is pretty high.

How many memory stick do you have? 2 or 4 ? If you have 4 sticks then I highly doubt all 4 will get damaged in same time unless the motherboard was the first one that died and destroyed other things when it decided to die. I said I doubt but I have to ask you if you tried to overclock the ram and pushed too high the V for it (default ddr2 voltage is 1.8V (there are some sticks that require more but they should have a freq that will allow u to run them to 1.8V else it will be imposible to use them first time u put them in the pc)).

Look at the memory modules if they look damaged in any way. If they look ok try to smell them, if all smell like something burned then nothing can be done in their case and also I doubt the mb is ok (unless u have set some crazy V for memory.). Do the same with the mb. If the memory sticks & mb look ok and don't smell like something burnt then: try to get a psu from a friend and test your pc with it, if it acts the same, then either the memory or the mb or both of dead are dead, next step will be to test in a friend pc the cpu, gpu, other pci-e/pci, hdd, etc. to see if they are ok or not. Keep in mind that it's always posible to destroy your friend mb when you test them.

L.E.: Unplug the 4/8 pin connector from your motherboard, put at least 1 memory stick and try to start the pc , you will have no post messages i know , but it's important to know if the fans start to spin or not. If in this case the fans start to spin then the psu died (when a psu dies it can take destroy the mb + others things or not, it depends from case to case) or at least it's no longer capable to power up your pc (as time passes the things in the psu get older and the real W will be reduced) ). You will still need to get a psu from a friend and see how it acts with another psu.