Piecemeal upgrading possible? (for 3D modeling+gaming)

[sinfulgurorose]

I'd like to preface this by saying I know jack about hardware, which is why I'm coming here for help. I need a computer that can run 3D modelling software well and play games at least 30fps.

I currently have a system I'd like to upgrade to save on costs. I don't know if it's possible, but I'd like to buy parts one at a time to slowly rebuild my system so I can get the best parts possible without having to break bank all at once.

Right now, I have:
CPU: Intel(R) Core(TM)2 Quad CPU Q9400 @ 2.67GHz
Motherboard: HP Compaq dc7900 Convertible Minitower
Memory: 8GB DDR2
Storage: ST3160318AS ATA 150GB & WDC WD3200AAKX-001CA0 ATA 300GB
Video Card: AMD Radeon R5 220

 

[gaius_iulius]

Sure it's possible to upgrade your rig bit by bit, in order not to break the bank and to wait for special offers on selected parts.

Some components must be installed together, however, since they would not be compatible with your current configuration, but will be necessary for the new system.

One way to go about it piece by piece would be like this:
1) New Power Supply Unit (PSU), should the one you have now not be sufficient for the new machine. (You didn't state what PSU you have now, so no way to say if it'll do.)
2) Motherboard & CPU & RAM. Those three components should be installed together, for obvious reasons. Different mobos support specific CPUs and specific RAM types and sizes only. Of course it's not a must to buy them on the same day, if your budget doesn't allow for that, but they should definitely be installed together, not piecemeal.
Decide on the CPU you want, then get a fitting mobo and finally the memory. 8GB of RAM will, do, 2x4GB as a Kit preferably.
3) Storage. If you can afford it, get at least one SSD, the difference in performance is significant. Use it for your OS and the most frequently used applications. Data such as photos and videos can be stored on a regular HDD. A 250 GB SSD (Samsung 850 EVO is about the best you can buy) will cost approx. 90-100 bucks (500GB cost 160-170), 2TB HDD is around 60-70.
4) Graphics card. Wait with that, prices are through the roof at the moment. Hopefully the crypto currency mining bubble will burst soon. If you have around 300-330 bucks to spend on that, a GTX 1060 will make you happy for some years. Alternatively a GTX 1050 Ti (approx. 200 bucks), since you said you'll be happy with 30+ fps.
5) Peripherals.

Cheers,
Gaius

Edit / P.S.: I'm just reading your original post again ... think about a new case, too, maybe. A Minitower is awfully small for proper components. Maybe you can get it in Step 1, together with the PSU. If you don't need something fancy, 60-80 bucks will get you a solid case.