Aspire ATC70A-UR12 won't recognize replacement video card - PC won't POST

Hi - hoping for some assistance.

Trying to replace the onboard graphics with a new Sapphire RX 470. My ATC70A-UR12 (i5-7400, circa 2017) has an aftermarket Corsair 600W power supply which has been running fine for months. When I install the RX 470 and power on, the CPU fan and HDD spins up, but the GPU fans never turn and the PC won't POST. The monitor remains dark of course.

Power down and pull out the RX 470. Then power on, and the PC happily POSTs and boots to Win as expected with the onboard GPU. Have tried a bunch of things as below, but the result is always as described previously: no POST

What I've tried:
- successfully updated BIOS to latest version from May 2018
- set BIOS Secure Boot to Disabled. Note no ability in BIOS to disable onboard GPU or set video card priority - the options are grayed out.
- disabled onboard graphics in Win10 Device Manager
- reseated card in PCIe slot a bunch of times.
- rechecked and reseated 6+2 aux power connectors to the RX 470.
- swapped 6+2 aux power connectors
- inserted an old working video card with an 'always on' fan. That card won't POST either, but the fan spins on power up telling me the aux power is good. Since both cards behave the same suggests it isn't a bad card.
- tried connecting monitor cable (DVI-D) to the RX 470 by itself. Tried connecting to the onboard graphics by itself in HDMI and then VGA. Tried connecting cables to both the RX470 and the iGPU simultaneously.

Thanks

Accepted answers

MetaMudd

Short version: Bad PSU was not delivering power on the 6+2 GPU power cables. Replaced PSU and GPU card worked as expected.

Long version: Replaced the 5 years old Corsair CX600 with a new EVGA 550 PSU. Applied power. GPU fans spun and the computer POSTed, but monitor did not detect the DVI output. Restarted computer. Monitor detected output. Booted into Windows as normal. Installed GPU drivers in Windows. Computer working normally.

Incidentally, the GPU I installed is an EVGA Sapphire RX470 dual fan. It is about 9.5 inches long and necessitated relocating the HDD to the upper bay in order to accommodate this relatively long card. Still a tight fit.

-Mark

All comments

Rufusevengaming

I may not have a solution but I have a similar CPU and tried to upgrade power and GPU. Same thing. What i finally did was go back to the original power supply (which was able to handle the 1050ti gpu) and I was up and running. If I were you I'd start with the power supply. Could be the problem...hope you get lucky!

MetaMudd

The original 300w supply will definitely not handle a RX470, but I can’t yet rule out the PSU as the problem either (my Corsair cx600 is 5 years old).

i’ll need to go buy a new psu to test.

-Mark

ikke_369

check all the voltage lines of the 6+2 gpu cables first, u can find what gives what voltage on internet.

MetaMudd

Short version: Bad PSU was not delivering power on the 6+2 GPU power cables. Replaced PSU and GPU card worked as expected.

Long version: Replaced the 5 years old Corsair CX600 with a new EVGA 550 PSU. Applied power. GPU fans spun and the computer POSTed, but monitor did not detect the DVI output. Restarted computer. Monitor detected output. Booted into Windows as normal. Installed GPU drivers in Windows. Computer working normally.

Incidentally, the GPU I installed is an EVGA Sapphire RX470 dual fan. It is about 9.5 inches long and necessitated relocating the HDD to the upper bay in order to accommodate this relatively long card. Still a tight fit.

-Mark

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