JaniceWLVSome inputs for low cost upgrade if it helps save your money:
- Assemble the TX3 fan as pull configuration.
- If the casing fan has grill, remove it. If you have to, cut it out.
- What is the ampere of the casing fan? Is it 0.17A or 0.23A? Look for something around 0.3~0.5A.
- If you open the case to cool the CPU, concern is that other critical parts like harddisk are not getting sufficient cooling. Reason being, computer casing is designed to have certain air flow for ALL components.
- Suggestion, instead of open side panel, make holes on the side panel. Focus on getting a few near the GPU, so that the intake of the GPU is getting fresh air from outside, through the side panel holes.

- For the GPU, does the hot air go out only through the rear casing, or also goes out at the front?
- If hot air comes out from the heatsink through both directions, then you will need an exhaust fan at the front of the casing. In this scenario, you'll have two exhaust fans.

- For the CPU, suggest you go to BIOS, and run the core voltage at slightly lower than stock. Reducing 0.125V or 0.25V for a CPU can reduce a lot of power consumption and heat.

Up to you.
If you have a drill, use a metal bit and back the panel on a solid piece of wood when you drill through.
If you want to use screw driver and a hammer, also can.
One forumer just used bullet holes, for real.