I'm guessing that you are talking about an nVidia chipset. But we do need more information - system configuration, a better description of the problem, and what you have done prior to asking for help.
What is happening is that you system has successfully completed the POST. That's what the "7F" is telling you. Stuck at "7F" and not going to "FF" indicates that you do have a problem actually booting the operating system (OS).
Possibilities:
Bad or uninitialized hard drive (if you just installed Windows, that's not it)
No OS installed (same)
System cannot find the OS. You need to tell the BIOS which drive and partition the OS is on. Your motherboard manual can help. This is usually caused by not plugging the boot hard drive into the SATA0 port (BIOS default for booting). If the drive is plugged into a different SATA port, you can either move it to the SATA0 port (always my choice) or go into the BIOS and change it.