Depending on what AMD you had prior you might need DDR3 RAM for this Core i5 that you cant migrate forward if prior system was DDR or DDR2. Any cards you had plugged into the prior system should be able to migrate forward to your i5 build as long as the new board has a legacy PCI slot if you have a need for a PCI card from prior build moved to this one. Case can be reused if its a universal case such as if it was a custom built system prior then its no problem as long as its large enough for the new motherboard etc. If its an old off the shelf computer it will likely have a front panel connector that is specifically pinned for the board that the system came with and there is no standard. I have had to cut the wires and patch in a universal front panel wiring kit to a Compaq case for example to take a motherboard upgrade. This universal wiring has Power Switch, Reset Button ( if it has one), Hard Drive LED, and Power LED ( if it has one ), and sometimes PC Speaker connection if not already on board as a piezo, so it allows connection of all motherboards of a ATX, mATX, and ITX and maybe some others. Power supply might be ok if its 350 watts or better and good name brand. However the power supply is one of the most important parts in a computer and so if you reused your old power supply and it dies in a way that over voltages your main board it can kill your new build. I have cut corners and used old power supplies before and most of the time no problems, however a few times the new motherboard was heavier power draw and the weak power supply stood out as unable to take the load and then i had to buy one. Additionally I had a build that ran for almost 18 months on a power supply out of a Pentium 4 build that i got a 20 to 24 pin adapter kit for, but for the cost of the adapter i should have just bought a new power supply however i had a stack of Pentium 4 - 20 -pin power supplies and saw this adapter as being a way to migrate old power supplies forward. And it worked ok, but i took the risk of burning up my new motherboard etc.
