New PSU + GPU (RX480) causing reboot loop

[seppy93]

OS: Windows 10 Home 64-bit
Motherboard: Dell 0KWVT8
CPU: Intel Core i7 4770 @ 3.4GHz
GPU: Radeon RX 480 GDDR5 4GB CrossFire
PSU: EVGA 700 B1, 80+ Bronze 700W

I recently installed the GPU and PSU. The PSU works fine when tested with the monitor plugged to the motherboard without the GPU. However, when I put in the GPU, a few things has happened.

Initially, when I booted the computer with the GPU, the motherboard made one long beep then 5 short beeps. Looking around, I saw that this indicated Real Time Clock Power Failure, and a suggested solution was to remove the plug and the motherboard battery, then hold the power button for 30 seconds to discharge. After trying this, the computer no longer beeps, but instead automatically reboot after a certain interval. In all cases, I cannot get to BIOS unless I remove the GPU.

If I plug one monitor to the motherboard and one monitor to the GPU, the former gets signal, but doesn't get past the logo screen.

I did uninstall the old driver, and then later install the driver for the new GPU before plugging it in. Also tried disabled secure boot. Unfortunately, the old power source is 6-pin, so I cannot use it to test if the new power source somehow doesn't give enough power when the GPU is plugged in.

Could someone suggest me some solutions, other than updating BIOS? I am not experienced with that, and certainly don't want to spend even more money for a new motherboard.

 

[hang-the-9]

OEM motherboards tend to have issues with newer video cards. First update the BIOS, not sure why you don't want to do that. It has solved video card compatibility issues for others. The power supply is good enough to run the video card, I'm leaning towards a motherboard incompatibility with the new card. If a BIOS update does not help, you can try running the card in another computer that has a non-OEM motherboard, so a stock ASUS, MSI, Gigabyte one, not from a Dell, HP, etc... system.