Your CPU and motherboard might be the ones causing the bottleneck for your system.. You have an am2+ board with a phenom x3 while your son has an am3 board.. Since I'm in the mood to answer some questions, LOL I'll make my reply to your problems as comprehensive and informative as I can..
1. Your CPU and motherboard are the most likely cause of your bottleneck to your system, the GTX 650 Ti even though it's an entry level card compared to the 660 Ti and above will play games at ultra/high settings in any resolution at a decent FPS.. I myself have played Far Cry 3, BF 3, Borderlands 2 and many more with the GTX 650 Ti at ultra/max settings @ 1440x900 with FPS around 30-60 depending on the game I'm playing, so your GPU is not the problem!
Am I able to upgrade to better ram?
Speccy did not specify what model your motherboard is but most likely from what I searched this is your motherboard: <click this link to hp site>
.. You have an am2 motherboard,
Socket type: AM2+
Motherboard supports the following processor upgrades:
Phenom with Quad Core (Agena) technology (AM2+) up to 9600 (up to 95 watt)
Athlon 64 X2 with Dual Core technology X2 up to 5600+ (up to 89 watt)
Athlon 64 less than 4000+
Sempron less than 3800+
Dual channel memory architecture
Four 240-pin DDR2 DIMM sockets
Supported DIMM types:
PC2-5300 (667 MHz)
PC2-6400 (800 MHz)
Non-ECC memory only, unbuffered
supports 2GB DDR2 DIMMs
Supports up to 8 GB on 64 bit PCs
Supports up to 4 GB* on 32 bit PCs
32 bit PCs cannot address a full 4.0 GB of memory.
So yes, you'll be able to upgrade your RAM to a total maximum of 8GB RAM provided you use 64bit Windows, and 4GB of RAM running in 32bit Windows.. And no you won't be able to use any DDR3 RAM sticks.. As for the scarcity of DDR2 RAM, DDR3 is more common nowadays and there are no new generation motherboards that are using DDR2.. Also you'll only be able to run your RAM @ 800Mhz
Also your motherboard's PCI-E x16 slot might be only 1.0 or 2.0 I think which will limit the bandwidth that your GPU can use.
Hence the old motherboard causing the bottleneck..
You can't upgrade to an am3 socket processors or Bulldozer/Steamroller (AMD's newest line of desktop processor)..
Now let's go to your stepson's motherboard and cpu.. Your stepson has this motherboard: <click this link to biostar site>
As you can see, it is an am3 motherboard, capable of support AMD's awesome phenom x4 and x6 processors that even though they are old they still pack a punch especially when overclocked..
Support Dual Channel DDR3 800/1066/1333 MHz
2 x DDR3 DIMM Memory Slot
Max. Supports up to 8GB Memory
So you can see your stepson runs his RAM at a very noticeable frequency hence the large difference between your system along with the CPU performance.
1 x PCI-E x16 2.0 Slot
2 x PCI Slots
HP neither speccy nor HP mentioned what type of PCI-E slot your motherboard was but your stepson has a 2.0 slot and yours is probably 1.0, hence the bandwidth difference..
The two motherboard also has a different chipset so yes, even though you have the same videocard upgrade, no matter how powerful that GPU is, GTX 680 or HD 7970, the CPU and motherboard will drag that GPU's performance down..
Other than your CPU and processor, your HDD's are fine if they are not defective yet..
Also if you will get an upgrade in motherboard and processor that will surely fix this problem..
Side Question: What power supply do you have? Your stepson's?
Tips and Tricks:
Alwasy check the motherboard's site, they will mention in the specifications tab what type of RAM slot you have, DDR3/DDR2/etc2 along with the support frequency that it can run the RAM at..
Check the motherboard's CPU socket type, am2+ motherboard will be able to support am3 processors (phenom x4 or x6) but will require the latest bios if your motherboard has one that allows you to support those am3 processors.. (Hence the term "+" in am2+, same goes for am3+ motherboards, they will support FX Bulldozer and FX Steamroller and most probably AMD's next line of processors) The motherboard's site will also indicate the socket type so you just have to search there.
Also PCI-E 3.0 GPU's are backwards compatible with PCI-E 2.0 slots, but there is the difference in bandwidth..