Well in that case I can't help you.
First you need to find those memory chips that will be compatible with the RX570. Maybe removing them from a broken RX 570 8 GB GPU card or other compatible RX 5xx GPU card. Then you need to have the equipment to remove and re-solder the new Memory chips to the Rx 570.
Anyways, if are able to do it without costing more then a new GPU card then good for you.
Take care and may be some other Users might be able to help you.
but you need to translate your answers from your native language to English since this is a English Only Forum. Thanks and good luck.