the gpu cannot install driver, testing vram with mats give an error 512mb. if the driver not loaded gpu is working normal.
I've tried rehot the crystal.

is this broken gpu crystal?

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google translate :
ГПУ не может установить драйвер, тестирование врам с матами дает ошибку 512мб. если драйвер не загружен, gpu работает нормально.
Я пробовал перестрелять кристалл.

это сломанный кристалл графического процессора?

If you are not sure about the originality of the BIOS, you can flash the original or at least a similar BIOS from the TechPowerUp website. Also try "diagnostic warming up the GPU", if after warming up the card installs the drivers and passes all the tests, then the GPU crystal has most likely fallen off.

i think 512M show error as exptected ， never heard anyone use 512M to test, maybe over design spec , so show error, 150M you also can got pass result ,i think VRAMs are good.
You can not install driver, maybe try flash bois , or check device HWID

after your increase test VRAM size ， seems A0 has some problem , it should be B face ,and close to PCIE VRAM , you can try to use MODS to test 118 or over VRAM clock 10% try to get which is bad memory. hope you get positive result

use mats over memory clock to test which video memory fail.