I have a acer aspire xc 703 sff,i was hopping to change the motherboard

The Aspire XC-703 desktop has a DTX size (243mm*200mm) mainboard with a Socket BGA1170 cpu with DDR3-SDRAM and a 220W PSU, if you want to use all the components that your desktop has then you will need to get the same size and spec mainboard which is going to be hard to get and you will not get any huge performance advantage with any upgrade so consider that seriously. In my opinion you would be much better off buying a new Aspire XC-1780 desktop with the Win-11 OS and a Gen 13 cpu and DDR4-SDRAM as it would be a much better upgrade and investment for you than upgrading the old XC-703 desktop.

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Your motherboard is a standard size, but laid out to deal with the extra thin case. That means that though you can fit most any uATX motherboard physically in the system, some issues might bite you. Note that the M.2 slot for the SSD is designed to have the SSD sit out to the side of the MB. Other designs will likely have that in a different location. More importantly the heat sink on the CPU is fairly short, standard heat sinks will likely interfere with the case.

At just about ten years old, you would likely be better served by purchasing a newer system than upgrading this one. Get something with a more standard mini tower and new enough hardware to run Windows 11 (so nothing over 5 years old or so).