I want to buy a new gigabyte gtx970 g1 gaming and i don't know if my switching power supply (atx-1000w) is good or should i change it
It will work with:
Amd fx9590
Gigabyte 990xa-ud3 motherboard
Even so, you have a 'no-name' PSU. 1000W has plenty of power. I would not use it myself. I just do not know how much the FX9590 has degraded the PSU. Form a technical specification situation, you would be good with an excellent 650W PSU.
The power use of that card is quite low. The power of the PSU at 1000W is enough. I am unfamiliar with the brand, but it is quite possible that the load of the FX9590 and the age of the PSU have conspired to use up most of the 'goodie' in your capacitors.
Even so, you have a 'no-name' PSU. 1000W has plenty of power. I would not use it myself. I just do not know how much the FX9590 has degraded the PSU. Form a technical specification situation, you would be good with an excellent 650W PSU.