Is it possible that if your PSU isn't good enough and you bought a new card the

Well, the HD 5770 should be fine with 400W, but Forton sounds generic and it could just be a bad PSU.

I didn't understand generic, but people told me Forton is a good brand.
I'll just leave the pc for half an hour and see what happens.

I wouldn't jump to conclusions  

It is entirely possible that your PSU is perfectly fine but your card is faulty

Generic is a sort of off brand (wal-mart's (r) great value(r) brand is a generic brand)

So generic is usually cheaper and sometimes cheaper quality

What is the amps going to your 12v rails(look on the PSU)

http://www.guru3d.com/article/radeon-hd-5770-review-tes...

This says that combined, your 12v rails should have a total of 40 amps

Does your psu have enough ?

Hope this helps

Uber

Fortron Source alias FSP group is not considered a generic brand they are a quality brand that has been around for many years! http://www.fspgroupusa.com/

I've now seen that it isn't the card, I replaced my old gpu 9600GT) and it's the exact same story. I should mention that I uninstalled my graphic drivers before installing the new gpu, so I don't have any drivers now. Does this affect this? I saw the desktop for three minutes, but then it got black.

So you didn't install the drivers that came with the GPU?

Boot into safe mode(F8 then choose safe mode) and install the drivers

Did you plug in the PCIe 6 pin power from the PSU to the card?

Hope this helps

Uber

O and if possible...get driver cleaner and run that in safe mode before you install your current cards drivers

I mean, I'm not sure if the card even fits.

No, I haven't installed the drivers yet, I'll do that. But before I do that, is it normal that the cards metal "small plates" are about 2mms (milli meters I guess) above the place where the screw goes into? I can only screw one screw in. Sorry that for that I'm not using the correct terms.

Nevermind the post two posts above, it fits better now, but I'm still unsure if it fits.

It almost booted in Safe mode, the logo appeared and then the screen displays the message: The current resolution can't be displayed, the message has long vertical lines in it and it seems like it's corrupted. That message appears every time I try to boot it, but I hear the bip when it's booting. This is killing me ._.

Make sure the card is seated correctly...this could cause problems and what your were explaining earlier...it very well may be the problem

I had the same fear(breaking the card) when i installed my first

If it is a PCIe slot then it will fit...it will be a little stiff to get in there but as long as it has ample room for its length, a little extra force should not effect the card

If it is seated correctly and power is too it and it still does that(lines and crashes) I would put my money on it being a defective card

Thanks and hope this helps

Uber

It turned out to be much more of a problem, the screen is bright blue now, it crashes when the ATI Catalyst center is installed, the pc doesn't read the driver cd, I think I have to take my comp to a local computer expert, he has helped some of my friends with pc promblems. But thanks for the support.