PC won't boot with new GPU

ImaqtLasagna

Prominent
May 1, 2017
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Hi everyone, today I have been trying to upgrade an old pc. Specifically, I changed the old PSU (200W) with a new one (500W) in order to upgrade the old GPU (GT620) with a "new" 550 ti. Unfortunately the pc won't work when turned on, specifically fan are spinning and LAN cable light is on which makes me think the the new PSU is working, but the monitor will stay black not receving any signal (using a VGA cable, althought I tried with an HDMI which won't work either). I tried to use the integrated GPU of my g2030 CPU but the monitor won't receive any signal anyway. If I remove the new GPU both the old GPU and the integrated graphic card would work perfectly. My motherboard is an Aspire MC605, I read that there might be some issues with the defaul video settings of the BIOS but I am not exactly sure since the default device is set to [auto] and the BIOS won't allow me to change it.
Any help is greatly appreciated. Much thanks
 
I highly doubt that the old GeForce GTX 550 Ti is GOP (Graphics Output Protocol) compliant. It is most likely using a legacy VBIOS (Video BIOS). The GeForce GTX 550 Ti is older than the Nvidia GeForce GT 620 (OEM).

The UEFI BIOS, on the Acer Aspire MC605's motherboard, may not have legacy VBIOS support (i.e. CSM (Compatibility Support Module) option).