Upgrade

First step is to clean install the drivers.

• Download DDU here: https://www.guru3d.com/files-details/display-driver-uninstaller-download.html
• Use the default options.
• For Select device type, select GPU / AMD.
• Do a "Clean and shutdown". This will remove all old drivers (Intel, Nvidia, AMD).
• When it's finished and the PC is off, double-check that the GPU is seated properly in the PCI Express slot (top, long one) - it should click.
• Double-check that the PCI Express power (red connector) is connected properly.
• Reboot and install the AMD drivers.

CEX do test graphics cards as they work on a universal platform.

The reason they don't test RAM and CPU's etc is that they'd need multiple types of boards/socket types which isn't that feasible. It's also the reason why stuff gets incorrectly labelled very often in there, eg EEC Ram sold as normal Ram, etc.

Graphics cards though can be tested on a single PC setup for that purpose, they run them through Furmark or 3DMark or something of that kind.

They're still generally fairly clueless though. Had a guy in CEX tell me a card I traded in "failed due to overheating" because it reached 80c....a perfectly normal operating temp for tons of cards.

Anyway, they should have tested that RX470 and found it to be working OK, but might have slipped through the cracks somehow.

The DDU file comes in a 7zip self-extracting archive.

When you click it, it should ask "Extract to:" Click Extract and it should create a new folder called "DDU v18.0.5.9". That's where the actual "Display Driver Uninstaller" tool resides.

The fact you're getting a signal is good! I suspect it's simply a driver conflict from the fact your machine used to have a GTX 770 years ago & you were running with Intel drivers for ages.