mainboard replacement went bad ...

Hi,
I usually replace mainboards on my pcs and have things turn fine, but this time, this mainboard replacement simply has no solution from my part: I replaced a mainboard because my system wont stop freezing (reinstalling windows was leading to nowhere and all devices such as hds, ram,floppy,video+sound+other adapters were tested fine on other pcs)..so I did replace that mainboard by a similar brand new one...I did plug back correctly all devices but when the PC boots, the screen stays blank! In normal circumstances, when that pc boots, the front leds (for Hard Drive and Power) flash ..then stop flashing, then the HD led would flash from times to times for usual data activity on the hard drive....but this time, when it boots, the two front leds
stay green ....
I dont think it has to do with my video card since I tried it on other pcs and it work fine...
PS: When the PC boots, there are no beeps at all..simply silent boot up with the monitor staying blank (the monitor is also working fine when connected to other pcs!)
any clue??

What motherboard and cpu are you using?

Is power working properly?

Well, I've tried this before and said this before, and the one time I didn't take my advice, I got embarrassed today. I did some work on a friend's computer's a few weeks back. Played with a lot of things and finally found "what I thought" were "burned" spots on the MOBO. He had told me that the problems started occuring after several electrical storms and power outages, so I just told him his MOBO was probably shot since I saw what I thought was physical evidence. Well, today he told me he took out his CMOS battery and a bit later put it back in, and much to my dismay, that was all it tookl.

I hate when that happens. Might not solve your problem at all, but at the least it is a very easy thing to test for, for a variety of problems.

Believe me, I felt like a real schmuck today for not checking that.

Yeah, and I have had the moment of panic before realizing I forgot to plug the power cord back in, hee, hee

We all so stuff like that ... the good sign is if we are man/woman enough to gracefully admit and laugh at our little whoopsies and not be arrogant and stubborn. After all, this isn't brain surgery ... thank goodness!