Inspiron 530 can not be overclocked, no BIOS control.
To reset CMOS
1. Power off the computer and make sure that it is unplugged.
2. Open up your computers case. You need physical access to the motherboard to complete this procedure.
3. Find a circular, (mostly) silver metallic object on the motherboard. This is the CMOS battery.
4. CAREFULLY remove the CMOS battery and leave it out for about 15 minutes. This will flush the CMOS configuration and will reset everything to factory defaults.
5. Set the battery back into place and power on the computer.
6. The computer should then warn you that the CMOS configuration could not be found. You can either reconfigure it yourself or restore defaults. Restoring the default configuration should be fine.
If this not going to help, well try running Dell diagnostics - at the Dell splash screen tap the F12 key to access the boot menu and select the diagnostics. run the full diagnostics.
Report back.