memory mod for amd radeon r7 260x

[kokodin]

Hello, for almost a year i been trying to make something that seems impossible, or my testing software is lying to me and it works only i can't see that.
I been trying to mod a memory on radeon hd7790 or 260x from 2 to 4 gb, but it doesn't seems to be as simple as i first thought.
In theory 2 workstation graphic cards using the same graphical processor have 4gb of memory firepro w4300 has 4 256x32b layout and W5100 has 8x 128x16b layout all use gddr5 memory and internals of the bioses seems to be very similar so i was trying to wing it , but so far it seems either tserver can't show up 4gb memory for this model or something else is going wrong
I was able to track down pretty much all informations about decoding memory controller configuration from russian youtuber modbios website and my own reaserch.
I have traced boardview connections on pcb and compared them to rx550, all seems the same and there is no missing connections.
i even got exact the same model of the gpu i had boardview for to make sure .
At this point i probably should give up, but i kind of don't want to so i have some questions.

1. does anyone know what should happen if you install 8gbit memory modules and configure vbios to expect 4gbit ones, or solder 4gbit ones and configure bios to expect 2gbit
should the gpu start and work normaly only with half of memory, or should it stuck with black screen on startup? How should tserver react to it?

2. does anyone know how to disable memory channels on this gpu core? it would really help with testing. modbios youtube channel and his website show it in detail for most gcn graphic cards using 512 and 256 bit memory controllers, but not for 128bit cards

3. does anyone know how tserver should test firepro cards? most of the time i mod any bios i get unknown gpu errors or information that tserver failed to read bios and not even trying to test memory so i have no idea how to test if memory is working. many of my bios mods show in tserver tests that half of memory controllers work fine and half at all, so i am not even sure if it is my soldering or bios moding problem.

for disabling memory channels i would at least have to have a way to calculate checksums in red box, but since there was never any cutdown version of bonaire gpu core with 64 bit memory bus i don't even have any clue other than modbios videos about his testing suite of tserver ment for higher tier gpu's

i would really apriciate if someone smarter than me who actually work with amd gpu's for a while look at it or give me some pointers, otherwise it may take another year or two before i give up :P

[vitekus1020]

Hi, friend. tell me the model of the video card and who its manufacturer is. Post a photo from both sides. and dump the BIOS dump. also the memory marking you want to install. I'll try to help.

[kokodin]

vitekus1020 i apriciate the offer but i am not working on just one gpu, my goal is to decode red part for experimental reasons and be able to make gpu work wiith 1, 2 or 4 memory (or 8 in x16 config) modules in any given configuration.
There must be 4 working versions of this config for 32bit memory interface and 6 for 64bit, the only one we have is the 128 bit one with all 4 memory channels active.

Most r7 260x and hd7790 are build based on reference design with very few changes, and bioses from hd7790, r7 260x and even r7 360 should all in theory work regardless of the vendor who made the card. I was able to make hd7790 work with 360 bios with cut down memory size just fine even though drivers would not load automatically, after manual install everything was working normally. 2d and 3d.

I was also able to test what if situations from my first question by just trying 1gb bios in 2gb gpu and 2gb bios in 1gb gpu . They just work only with glitchy 3d when the memory buffer is declared bigger than phisically avalable. So i hope it be the same with bigger density chips.

I was able to confirm at lest that memory test would pass if i solder the memory corectly even if it is a bigger module, and decode 2 more blocks of the configuration string, not the red part though. I might update the image later.