Vega 64 - reset issue, 404 W power draw

[Prott]

Hey,
I have a problem with Vega 64. Unfortunately there seems to be no schematic, so I am going by what I feel might be the case for those two issues:

1. On restart the card doesn't seem to clear the VRAM and acts out (the picture stays on the screen followed by a black screen or artifacts till the drivers load). If I turn the computer off and on again the issue is solved and the card works flawlessly. PCI_RESET resistance is around 1.8 MOhm and the resistor between core and the reset pin is 0 ohm, as it should be. Is there anything else that could be causing this issue?

2. Card reports stable power draw as 404 W, which is causing the GPU to throttle. Does anybody know the location of the resistors inbetween the IC that reports the powerdraw and shunts? I assume the main IC (that also acts as a vcore/vmem voltage controller) is doing this job, but I couldn't pinpoint the connection to any shunts from there.

Thank you so much.

[Aliencomputres]

Re: Vega 64 - reset issue, 404 W power draw

Heloo,

black screen or artifacts its generated by the Vram issue.

[Prott]

Re: Vega 64 - reset issue, 404 W power draw

Heloo,

black screen or artifacts its generated by the Vram issue.

Thank you, I would think so too. But this happens only during restart and only when it restarts from graphic into "DOS mode". I think it's too consistent to be a VRAM issue.

1. From dos mode to dos mode: During restart the picture is not cleared (if I physically restart the board the same picture remains frozen - even with blinking cursor till new picture overwrites it).
2. If I restart from Windows it either displays artifacts till it returns to Windows or prevents the computer from booting.

Except those two scenarios the card works 100 %. I would imagine if the VRAM was going out the card would display artifacts at random times during load.

I will put it in my other computer and see if it's actually not a motherboard issue. The thing has been acting weirdly recently

[Prott]

Re: Vega 64 - reset issue, 404 W power draw

UPDATE: The 404 W power draw got solved by itself... which doesn't make me that sure it's solved.

However the PEX_RESET issue is still present. I changed the U100 and neighboring capacitor, but no change. As far as I can tell, except power rails (3.3 and 1.8) and ground, PEX_RESET only connects to the core. I will check the reset signal with a scope and update further for anybody else having this issue.

[Prott]

Re: Vega 64 - reset issue, 404 W power draw

Ok, finally got around to check the card with scope. The card's RESET signal is always high, no matter if I restart the computer or not. Normally it should go low upon restart for a moment, but for this card it doesn't.

In Vega the reset signal goes only into an AND gate, so somehow it seems as if this gate is backfeeding and keeping the signal high even if motherboard pulls it low. I already tried to exchange it with a gate from a donor board, but it behaves the same.

For some motherboards it means card works ok until restart, for most it doesn't even work at all.

Anybody experienced this issue? Thanks

[Prott]

Re: Vega 64 - reset issue, 404 W power draw

Ok, so this reset issue is killing me a bit.

I replaced the AND gate (U100) with a known good one and it didn't fix anything. I meassured following:

- resistance between PERST and PERST_BUF (signal after AND gate), it's around few kohm.
- resistance between PERST and 3.3VBUS is also few kms

What could prevent motherboard from pulling the reset low? This is, essentialy, the circuit (sorry about the mess).

I have a schematic for the ROG flavour of the card, so the base variant might be a bit different - which is where the problem probably lies. I can't find the "SU101" anywhere on my card. I wasn't able to find continuity between PERST and any other IC on the board.

Does anybody have any tips before I go completely mad?