Question New Build Can't Use Multiple Monitors

[S_K]

Here's my new build (see below). I tried use Nvidia T600 GPU, and the screen just kept blink and turned to dark. If I use the graphic output from the motherboard, it works fine. I figured that other hardwares, like motherboard, may be not compatible to T600 GPU. So I bought another GPU, which is visiontek radeon 7750 2gb gddr5 6 4k monitor graphics card. This is a 10 years old card but seems better compatible to the system. It can use one monitor with no problem. But if I connect another monitor, both monitors started to blink and the second screen will turn to no signal and the first one keep blinking. I have to disconnect the 2nd screen to make the one monitor work normally. Do you know what may cause this issue? Is it because of defective motherboard?

Thanks in advance!
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PCPartPicker Part List: https://pcpartpicker.com/list/TXzBYN
CPU: *AMD Ryzen 9 7900X 4.7 GHz 12-Core Processor
CPU Cooler: Deepcool AK620 ZERO DARK 68.99 CFM CPU Cooler
Motherboard: *MSI MPG X670E CARBON WIFI ATX AM5 Motherboard
Memory: G.Skill Trident Z5 Neo 64 GB (2 x 32 GB) DDR5-6000 CL30 Memory
Storage: *Western Digital Black SN850X 1 TB M.2-2280 PCIe 4.0 X4 NVME Solid State Drive
Video Card: VisionTek 900614 Radeon HD 7750 2 GB Video Card
Case: Corsair 4000D Airflow ATX Mid Tower Case
Power Supply: Corsair CX750M (2021) 750 W 80+ Bronze Certified Semi-modular ATX Power Supply
Case Fan: Corsair AF120 ELITE 59.1 CFM 120 mm Fan

 

[CountMike]

Here's my new build (see below). I tried use Nvidia T600 GPU, and the screen just kept blink and turned to dark. If I use the graphic output from the motherboard, it works fine. I figured that other hardwares, like motherboard, may be not compatible to T600 GPU. So I bought another GPU, which is visiontek radeon 7750 2gb gddr5 6 4k monitor graphics card. This is a 10 years old card but seems better compatible to the system. It can use one monitor with no problem. But if I connect another monitor, both monitors started to blink and the second screen will turn to no signal and the first one keep blinking. I have to disconnect the 2nd screen to make the one monitor work normally. Do you know what may cause this issue? Is it because of defective motherboard?

Thanks in advance!
-------------------------------------------------------------------------------------------------
PCPartPicker Part List: https://pcpartpicker.com/list/TXzBYN
CPU: *AMD Ryzen 9 7900X 4.7 GHz 12-Core Processor
CPU Cooler: Deepcool AK620 ZERO DARK 68.99 CFM CPU Cooler
Motherboard: *MSI MPG X670E CARBON WIFI ATX AM5 Motherboard
Memory: G.Skill Trident Z5 Neo 64 GB (2 x 32 GB) DDR5-6000 CL30 Memory
Storage: *Western Digital Black SN850X 1 TB M.2-2280 PCIe 4.0 X4 NVME Solid State Drive
Video Card: VisionTek 900614 Radeon HD 7750 2 GB Video Card
Case: Corsair 4000D Airflow ATX Mid Tower Case
Power Supply: Corsair CX750M (2021) 750 W 80+ Bronze Certified Semi-modular ATX Power Supply
Case Fan: Corsair AF120 ELITE 59.1 CFM 120 mm Fan

Those are old GPUs, probadly not all compatible with UEFI, Try one monitor in GPU and other one in the MB,

 

[S_K]

Those are old GPUs, probadly not all compatible with UEFI, Try one monitor in GPU and other one in the MB,

But T600 is not so old, which was released in Apr'2021, and seems like it's less compatible than radeon 7750 to the system. This is why I am thinking if other system hardware, like MB, memory chip, or other parts, is defective.

 

[CountMike]

But T600 is not so old, which was released in Apr'2021, and seems like it's less compatible than radeon 7750 to the system. This is why I am thinking if other system hardware, like MB, memory chip, or other parts, is defective.

If any of those were defective, it would equally reflect on any GPU.

 

[DataMeister]

I suppose it could be an issue with the PCIe bus. Did you try plugging the GPU into multiple slots to see if it made a difference?

Do you have the latest firmware on the motherboard?

Does the blinking happen in the BIOS screen or only after booting into an OS?

 

[S_K]

I suppose it could be an issue with the PCIe bus. Did you try plugging the GPU into multiple slots to see if it made a difference?

Do you have the latest firmware on the motherboard?

Does the blinking happen in the BIOS screen or only after booting into an OS?

It's on OS screen. I tested both Nvidia T600 and Radeon 7750 GPU on my old computer MB(Gigabyte GA-AX370M-DS3H) and they all work fine. The only issue of old MB is the 2nd PCIe slot is X4, so T600 can't run 4 monitors on it. Only 3 monitors can run and 4th one blinked and went dark.