after changing the ram now the screen is getting signal that means the machine is running fine with the modded PSU
No it doesn't. What signal? What do you see?
but the issue is a black screen
no post errors or bios or even Dell logo
Which are symptoms of possible power problems.
That said, "
no post errors or bios or even Dell logo" is contradictory and frankly makes no sense. I understand there may be a language barrier here, but proper grammar and punctuation would go a long ways toward mutual understandings here.
No POST (power on self test) errors is good. But how do you know you have no errors? Do you hear one, short beep indicating a successful POST? Do you see on the monitor that the system booted all the way to the point it hits the boot drive and starts to load the OS? Those would indicate a successful boot.
What does, "or bios" mean? Do you mean you don't see anything about the BIOS on the monitor during boot?
What does "or even Dell logo" mean? Do you mean you don't see that either.
Do you see
anything on the monitor during boot?
and now everything seems fine
Sure doesn't sound like it to me.
