Well both CPU and GPU are weak. But your GPU is much weaker than the CPU.
What power supply (PSU) do you have and how many amps are on the +12v rails. It would be best if you can take a picture of the PSU's sticker which list all the specs.
Also, what motherboard do you have? I'm guessing it is probably an old one what has a PCI-e 1.0 or PCI-e 1.1 slot.