VOGONS


First post, by byte_76

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I need some help please.

I have a Radeon HD3870x2 which is not detected by the PC. (Tested in multiple systems)

I removed the cooler and briefly started the PC while holding my fingers on both cores to confirm that both do get hot quite fast. On the rest of the board I cannot feel anything that is excessively hot with my fingers and I don't have a thermal camera to do a more thorough check.

With the card assembled, I booted into Linux and Windows using the onboard display adapter as primary and confirmed that the HD3870x2 is not detected at all. The cooling fan on the card does run and also seems to adjust it's speed slightly lower just after power on and otherwise the PC boots just fine but it seems entirely unaware that the graphics card is installed. (Again, tested on multiple systems)

I used a PCIe tester and confirmed that all lights are on. So the data lines seem to be okay.

I also confirmed that the LED's behind the power connectors turn on when the cables are disconnected and turn off when the cables are connected.

There is a bit of damage on the bottom rear corner of the card so it must have been dropped at some point but the damage seems to be fairly isolated and there does not seem to be many tracks in that corner.

I don't have much knowledge of electronics but I have a multimeter, LCR meter and hot air station.

I've not tried to measure any voltages while the PC is on (because the cores get hot too fast with the cooler off and when it's on I cannot access much) but since the cores do get hot, can I assume that all power stages are present?

Does anyone have a circuit diagram for this card?
What could be the issue?

Reply 1 of 4, by byte_76

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Is there anybody who can help me to troubleshoot this card?

Any schematics or boardview?

Does anyone know the power sequence?
Considering that both cores do get hot, would it be correct to assume that 12V, 5V, 1.8V and vCore are present?

Any ideas on what the fault might be and where to focus attention?

Reply 2 of 4, by byte_76

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I’m completely lost as to what the fault could be with this card.

It’s a special card and not very easy to find at an affordable price so I really would like to fix it if I can.

Would really appreciate any help.

Reply 3 of 4, by paradigital

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The lack of detection on the bus suggests to me that the problem is most likely to be at the PCIe data/lane circuitry.

A working video BIOS isn’t usually required for device detection, neither is a working video core.

Potentially a problem with the PLX bridge?

Reply 4 of 4, by byte_76

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It’s possible but I have my doubts because the PLX bridge gets slightly warm at power on and continues to warm up the longer it’s on.
I also tested with a PCIe tester and all LED’s light up. I believe most of those tracks go to the PLX bridge.

I have a mining adapter which allows me to lay the card flat on my bench while I test.

I could measure some voltages but I need some help with where to measure and what to expect.

Any ideas? (What else to check)