ECC RAM is for Server and Workstations but some Desktops do support it... ECC is supposed to be more expensive so they probably offer lower prices to get rid of stocks, but to some extent also because ECC ram is 2-3% (which is not much) slower than Non-ECC (Error Correcting Code) though RAM may only check for errors, and not correct them... there is also buffered and non buffered ECC RAM.
It all sums up to what your motherboard can handle, some can use both types so it would help knowing with a System Information program that shows detailed system memory information.. HWiNFO shows that info under Motherboard/SMBIOS/Memory Devices/Memory Controller... but if it shows your motherboard supports ECC RAM, you will still have to search for information from the motherboard manufacturer that confirms it.
Advantages of ECC Memory
http://www.pugetsystems.com/labs/articles/Advantages-of-ECC-Memory-520/