Because the N1996 mark covers multiple desktop architectures, these boards generally fall into three main historical eras: LGA 775 (Intel Pentium/Core 2), AM2/AM3 (AMD Athlon/Phenom), and LGA 1155/1150 (Intel Core 2nd to 4th Gen).
First, a critical note: The model number "N1996" is often a rather than a retail model name (like MS-xxxx). In many cases, the N1996 corresponds to the MS-7369 (v1.x) or a similar Verde Valley series board. AM2/AM3 (AMD Athlon/Phenom)
If your computer is still functional, you can identify the model without opening the case: AM2/AM3 (AMD Athlon/Phenom)
Disclaimer: The information above is based on common N1996 variants available during the 2021 research period. Always verify the MS-XXXX model number on your motherboard. If you'd like, I can: AM2/AM3 (AMD Athlon/Phenom)