Maximum PC

My PC randomly crashes lately. The screen would be black but the PC is still running. When I power down the PC
using the power button and then switch the power button again in about a minute, the screen would be black, the POST screen does not show but the I can see the PC powering up and I can hear the Windows 7 welcome sound.
Even as the screen is black I can shut down the PC using the PC shutdown shortcut (Winkey+right arrow+enter). I can hear the shutdown music when I do this.

If I wait an hour and boot the PC, the POST will show and the PC will boot normally.

I am wondering if this is a videocard problem?

I tested the memory using the Win 7 memory test and it says it is okay. I am monitoring the temperatures using
Core Temp and the values are around 60 degrees at most.

My specs: one year old PC, Intel i5, ASUS P8 H61-M LX mobo, Nvidia 450 GT videocard

Just so I can get it off my chest: this isn't a crash. A crash is complete system failure. A BSOD is a crash. Video going kaput is not a crash.

Anyway. Try power cycling the monitor when this happens, swap which port the monitor is plugged into on the video card, or change the cable.

@LatiosXT, I stand corrected, it wasn't a crash.

Anyway, I don't think it is a monitor problem as the monitor will say that it is going into power saving mode
when the screen is black. I understand that when this prompt from the monitor appears it means the monitor is not receiving a signal. I tested the monitor in another PC and it is working fine.

I just replaced the videocard with a better one. Problem solved.