AMD Polaris GPU Diagnosing Guide

'This guide is applicable for most polaris cards from 460 to 590, some vendors may create different PCBs or use different components but the general working principles for all of them should be the same unless specified. This guide uses a reference RX 480 as an example.'

-UNDER CONSTRUCTION-

The Card.
*PCB Image courtesy of TechPowerUp*

Before doing anything, it's a good idea to inspect the card for physical damage. Especially cards that have no backplate. They can easily lose some components on the back due to poor handling.

After making sure there is no physical damage to the card itself you can now move on with a multimeter to check the resistances of the voltage rails.

Step 1: Base Voltage Rails (12V, 3.3V)
The base voltages are the ones that get supplied to the card through the motherboard and the external 8pin power connector(s). What are the Base Voltage rails for GPUs?

12V rails
The card gets supplied 12v through the PCIe slot and additional 6-8 pin connector(s)

Start by measuring the resistances of the 12V rail coming from the PCIe slot (first 3 pins, see figure 1).

After that, measure each inductor for external power connectors (some cards have multiple external power connector and each of them have their own inductor you have to measure each of them individually).

The resistance varies from card to card and the value itself doesn't matter but it should be in the thousands+ Ω range.

3.3V rail
The card gets 3.3V from the PCIe slot only, from the 4th pin going left from the PCIe key notch in the front, and 2nd and 3rd pins on the back going from the notch again. (Figure 1 and 2)

If you get less than 50Ω on one or multiple base rails then you have a card with a short. The computer might not turn on in such a case because the power supply is protecting itself using OCP (over current protection). Repair Guide: Base Voltage Rail Short on Polaris GPUs

Otherwise, if you have no short then you can continue troubleshooting.

Step 2: Minor Voltage rails. (5V, 1.8V, Display Rail, VMem, VCore, and VDDCI)
Minor voltage rails are the ones created by the card itself using the base rails through either Linear Voltage Regulators or Step Down Buck Converter

Check the resistance of the output of those rails and compare them with Figure 1 and 2. VCore has such a low resistance that you won't find it useful to measure its resistance. A more helpful way is to measure its resistance against the 12v rails not GND.

If you get lower resistance on one or more of those rails, head to their pages linked below.

Otherwise, continue with the guide.

Step 3: Powering on the card.
Assuming you have no shorts anywhere you can go ahead and plug the card into the motherboard and start testing (Alternatively, you can use a Lab Bench Power Supply and a riser to test the card with. Safer for the motherboard and gives you more freedom to move the card around and you get to know the current draw of the card if there is a short).

Switch your multimeter to DC Voltage mode and start by measuring the base rails first, if they are present continue to the minor rails.

Minor rails turn on in series, if one doesn't start, the next ones in series will not turn on.

Power sequence
The order in which they turn on in most polaris GPUs is as follows:

5V→ 1.8V→ Display Rail → VMem/VDDCI → VCore. (In some cases, VDDCI turns on after VMem, while in other cases VDDCI and Vcore are controlled by the same controller and they turn on at the same time)

For example, if 5v does not turn on, everything else in the chain won't turn on either. Hence no fan spin if you have a problem with 5V or 1.8V.

If you're missing one of them, check their respective pages for more details on how they work and their potential problems:
 * 5V Rail on Polaris GPUs.
 * 1.8V Rail on Polaris GPUs.
 * Display Rail on Polaris GPUs.
 * Vmem Rail on Polaris GPUs.
 * VDDCI Rail on Polaris GPUs.
 * Vcore Rail on Polaris GPUs.

Step 4: No Video Out.
Everything is present but still no video out? You may have faulty Memory, Bios, PERSTB, GPU chip itself, or in some cases a problem with straps.

Memory problems
If you've reached this point, the most likely culprit is the Memory. You can confirm this by testing the memory in Linux. Here: AMD Memory Testing Guide. is how to detect the faulty memory chips.

BIOS problems
If the memory is okay or the card is not even being detected in Linux then the problem is highly likely to be the bios. Check: BIOS Problems on Polaris GPUs.