pre-built has turned into a nightmare, please help

intro:
Hey there, Acer Community. Not so long ago I've bought a gpu with the intent of upgrading my pre-built. That pre-built being the Aspire TC-780 UR12, has been painstaking for me as I've gone through vast amounts of forum pages with no luck what-so-ever.

specs:
https://www.cnet.com/products/acer-aspire-tc-780a-ur12-tower-core-i5-7400-3-ghz-8-gb-1-tb-dtb7yaa002/

modifications:
psu - manufacturers to a 550w powerspec, manufacturers was used to power rest of system while 550w psu 8pin connector only was used for gpu
gpu - gigabyte radeon rx 580 8gb

problem:
Whenever installing the gpu I would get no display to my monitor. To confirm, yes I had the HDMI connected to the gpu. Each and every time I turn on my pc with the gpu installed, the power button light for the pc would be off while the gpu led lights work on-startup. The fans for the gpu also do not spin on-startup either.

Accepted answers

StevenGen

This problem is common with the Aspire TC-780 with its Intel H110 Express chipset which also common with the newer TC-855 that has the same problem with the RX 580, to me it seems that the mainboard is at fault here and this gpu is not compatible with the OEM board and gives the same problems on both models.

I think the mainboard does not supply the needed "Typical Board Power of 185W" that the RX 580 needs to be able to power the RX580 as your PSU upgrade is ok, as the recommended PSU for the RX580 is a 500W. Other gpus do work with both Aspire TC-780 and the TC-855 e.g. like GTX 1060ti’s etc, there must be a power issue that the RX580 is not happy with on this board.

What I would do (depends on your budget?) is upgrade to a newer mainboard (that you can virtually swap all components to) and with a newer chipset like the B250 that the Intel i5-7400 7th Gen cpu’s will also be compatible and upgradable to. Try to match the brands as I'm sure that Gigabite made the Gigabyte Radeon RX 580 8GB to be compatible with their mainboards like the "Gigabyte GA-B250M-Gaming 5 (rev. 1.0)" board that has the 1 x PCI Express x16 slot, running at x16 (PCIEX16) (* For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot) 1 x PCI Express x16 slot, running at x4 (PCIEX4) 2 x PCI Express x1 slots (All of the PCI Express slots conform to PCI Express 3.0 standard.)

You can also try a more std board like the Gigabite GA-B250-FinTech (rev. 1.0) that will all handle a PCIe 16x and the 6th/7th Gen Intel LGA1151 Socket DDR4 Mainboard and compatible board to what the Acer OEM board does.

Gigabyte GA-B250M-Gaming 5 (rev. 1.0)

All comments

StevenGen

This problem is common with the Aspire TC-780 with its Intel H110 Express chipset which also common with the newer TC-855 that has the same problem with the RX 580, to me it seems that the mainboard is at fault here and this gpu is not compatible with the OEM board and gives the same problems on both models.

I think the mainboard does not supply the needed "Typical Board Power of 185W" that the RX 580 needs to be able to power the RX580 as your PSU upgrade is ok, as the recommended PSU for the RX580 is a 500W. Other gpus do work with both Aspire TC-780 and the TC-855 e.g. like GTX 1060ti’s etc, there must be a power issue that the RX580 is not happy with on this board.

What I would do (depends on your budget?) is upgrade to a newer mainboard (that you can virtually swap all components to) and with a newer chipset like the B250 that the Intel i5-7400 7th Gen cpu’s will also be compatible and upgradable to. Try to match the brands as I'm sure that Gigabite made the Gigabyte Radeon RX 580 8GB to be compatible with their mainboards like the "Gigabyte GA-B250M-Gaming 5 (rev. 1.0)" board that has the 1 x PCI Express x16 slot, running at x16 (PCIEX16) (* For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot) 1 x PCI Express x16 slot, running at x4 (PCIEX4) 2 x PCI Express x1 slots (All of the PCI Express slots conform to PCI Express 3.0 standard.)

You can also try a more std board like the Gigabite GA-B250-FinTech (rev. 1.0) that will all handle a PCIe 16x and the 6th/7th Gen Intel LGA1151 Socket DDR4 Mainboard and compatible board to what the Acer OEM board does.