Hello, my pc is completely dead. I can't do a thing with it. It started when my brother played on my pc, and when I wanted to play, my favourite game said: "Cannot run, faulty hardware settings or configuration"
I couldn't beleive this because I played this game a week without any problems (Mech Warrior 4 by Microsoft). So I shut down my pc, and looked inside my pc if everything was ok. everything looked ok, and I installed a new Sound card and a DVD-RW burner.(I never found the time to install them, so this moment was the right time to do it...)I closed my pc,wanted to boot, switched the power switch on, and... nothing, nada. It gave nothing, my pc was completely dead. I didn't get it because I normally know a lot of computers. I tried to set my pc to original configuration: Sound card out, my old sound card back in, dvd_rw out... But still nothing. a month ago I bought a new case, so maybe the power switch was disconected in my front panel, so I tried to use the power switch of an other pc, but still nothing. So the power switch is ok. Is my mobo fried? It's weard because my my scroll mouse was lit: the scroll wheel always lits red, even my pc is switched off. But it lit, so there is something of power in my pc, but no leds burning, nothing. I don't know what to do, is my mobo fried? This is my system: mobo: Tyan trinity s1854 rev.400, Ati Radeon 9200Se 128mb, Western digital 60GB, internal iomega zip disk 100, Creative DVD dx3 Encore 12x with decoder card, Soundblaster 128PCi, 3com ethernet card with wake on lan, Intel P3 667Mhz.
I had another idea: I'll try to use wake on lan to boot, but i need my pc's ethernet adress wich I don't have...
So i'ts a real mess, I don't know what to do, what can be the problem?
Is my new cases power supply inefficient?
Normally it should, it's standard ATX...
Help me please!

Ps: will I be warned by e-mail if someone replies?

First off, why would you start putting new stuff in when you were already having problems prior to the installs?
Secondly, you ask if the PS is sufficient, but never told us how many watts it is. Even though you see power to the mouse, your power supply could be bad. Start by removing everything except video card, ram and cpu (this includes disconnectinh the HD's). If the computer still does not power up, It's one of those 5 items (mobo, cpu, ram, PS, or video card). Some people even say to pull the video card to see if you get an error beep code. And of course if the computer does power up, start reconnecting one at a time for process of elimination.

We can fix this, but you're gonna need a butter knife, a roll of duct tape, and a car battery

ok, but it worked fine with my new case for more than a month. And I did first not having problems to prior installs, it just gave a problem when my brother played, I opened to check, it looked fine, and installed the 2 new components...

Angryman2001 is correct, listen to him and do what he says. By installing new components before you found the existing problem you only add to the difficulty.

If you knew enough about computers, you'd know that you need to fix problems before you try to add to it.

You should follow angry's advice. Get down to basics (psu, cpu, mobo, video, ram). If it still won't start up, try removing the video and ram (of course 1 at a time) and seeing if you get an error code. You can also get a cheap psu tester ($5-$15) to test your psu.

I'm leaning to a bad mobo, but you should diagnosis it first. Otherwise, if it was the psu, you could just fry a replacement mobo.

The PSU that come with cases are generic, which more often than not are bad/poor. The PSU is the backbone of the system...if it blows, it could fry everything in your computer (that's why pc enthusiasts go out and buy a cheap brand name psu first to replace the case's psu). I have several psu's sitting around in my garage hehe

Classic case of a failed cpu fan.