An x38 by default will support a quad core processor. Core 2 quads despite being old and inferior are pretty pricy. But if you can find one for a reasonable price then it might be worth it.
The manual shows full support for quads if you choose to go that route.
Spentshells is correct. Most likely there won't even be options for overclocking in your bios, since the PC is an HP. OEMs usually bar you from overclocking on their hardware, unless it's a custom desktop from alienware, Ibuypower, etc...
The 550ti has always been a bang for the buck turkey. It would match your system just fine but you could get a 250x which will be faster for about the same amount if not less if you keep your eyes open
An x38 by default will support a quad core processor. Core 2 quads despite being old and inferior are pretty pricy. But if you can find one for a reasonable price then it might be worth it.
The manual shows full support for quads if you choose to go that route.
The 550ti has always been a bang for the buck turkey. It would match your system just fine but you could get a 250x which will be faster for about the same amount if not less if you keep your eyes open
Your better off getting a new cpu and motherboard from this generation. It will most likely be cheaper AND give you more performance. Discontinued hardware tends to go up in price the longer time goes on, core2 hardware has been off the market for 5+ years now.