how can i tell if my PC working good?

Speccy
1
Motherboard
Manufacturer ASUSTeK Computer INC.
Model P7P55 LX (LGA1156)
Version Rev X.0x
Chipset Vendor Intel
Chipset Model Havendale/Clarkdale Host Bridge
Chipset Revision 12
Southbridge Vendor Intel
Southbridge Model P55
Southbridge Revision 06
System Temperature 29 °C
BIOS
Brand American Megatrends Inc.
Version 0805
Date 6/04/2010
Voltage
CPU CORE 0.936 V
MEMORY CONTROLLER 1.784 V
+3.3V 3.408 V
+5V 5.112 V
+12V 11.988 V
VIN6 0.248 V
2

you'll need to explain in more detail what you are after.

those specs are showing their age but it all depends on what you expect out of the PC.

no-one but you can determine that.