Please keep in mind that i am not a professional here, all this stuff is just a hobby and all i know is what i was able to figure out myself. Also English is not my native language, so if i mess up terminology please do not get annoyed.

Got "dead" AGP GF7300GT a few days ago basically for free, because it was assumed that GPU is dead in a typical way. Wanted to fiddle around with it, may be try heating the GPU up to make sure it is the issue and may be try swapping a GPU from the same pci-e card. This is mostly for fun and practice, i do understand that it is not really worth the time from practical point of view.

However when i plugged it in something seemed wrong - it started and worked fine for a minute, then basically turned off (no image, fan went to 100%, PC frozen) and never turned on again. So before messing with GPU i decided to do basic stuff like make sure there are no shorts (which there were none). Also desoldered a couple caps to see if those are ok. The caps were mostly dead - very, very out of spec, though they looked fine outside. I replaced the caps, but nothing changed.

Tried to measure voltages and it turned out there is no GPU vcore. Related transistors seemed fine, at least as far as they can be checked in circuit (no shorts). Digging around further (and comparing how vram supply works, which is fine, compared to vcore) it turned out that controller is the most likely suspect. All inputs seemed fine, but no output on UGATE or LGATE at all. So i swapped vcore and vram controllers and sure enough now vcore worked while vram did not.

So it seems that i have found the issue, though what killed the controller would be a good question... but given it is working with correct voltage and everything... may be the caps had a role here, or may be it just failed by itself?

Now to find a replacement... the controller is APW7065. I was not able to find a donor with specific one. However i was able to find one with APW7165. Looking at datasheets this seem similar enough for a direct replacement and pinouts are the same. However my level of understanding how this stuff works is clearly not sufficient to be 100% certain. May be someone with better understanding can offer some advice?

I do understand that ordering the correct part is the best way, but... it'll be half the price of such card and a looong wait (a couple of month), so not necessarily worth it.