When Only One RAM Slot Works: Decoding a PC’s Startup Problem


“Could you provide your expert analysis on a booting issue with a recently assembled PC? The system only initiates when RAM is inserted into the DIMM-A1 slot. Initially, the PC was functioning normally, but after a sudden freeze and forced shutdown, it now fails to send any signal to the monitor, despite active fans. Attempts to reset the BIOS and reseat the CPU have been made, with no success. Both RAM sticks are confirmed to work individually in the DIMM-A1 slot, yet neither functions in the DIMM-B1 slot. This has led to speculation that the motherboard or CPU may be unable to handle the RAM. The components are new and under warranty, and there has been no overclocking. The goal is to determine whether the issue lies with the CPU or motherboard to seek a replacement from the manufacturer. The system includes an Asus B450m MK-ll motherboard, Corsair Vengeance LPX 16GB DDR4 3600 MHz RAM, Ryzen 5 5600g CPU, AMD Sapphire Nitro Plus SE RX 590 GPU, and an EVGA 600 – 100-W1-0600-K2 power supply. Your guidance on this matter would be greatly appreciated.”


When faced with a PC that only boots with RAM in the DIMM-A1 slot, several factors come into play. The situation described suggests a problem that arose after a sudden freeze and forced shutdown, which now results in no signal being sent to the monitor despite the fans running.

The initial steps taken were prudent; resetting the BIOS and reseating the CPU are standard procedures. However, since these actions did not resolve the issue, we can rule out simple software glitches or seating problems with the CPU.

RAM Slot Functionality:

The fact that both RAM sticks work individually in the DIMM-A1 slot but not in the DIMM-B1 slot is revealing. It suggests that the RAM itself is functional, and the issue likely lies with the DIMM-B1 slot or related circuitry.

Motherboard vs. CPU:

Considering the motherboard and CPU’s role in handling RAM, the problem could be with either component. However, the motherboard is often the culprit in such scenarios, especially if the CPU has been reseated without any bent or broken pins observed.

Potential Causes:

  • Motherboard Circuitry:

    A fault in the motherboard’s circuitry connected to the DIMM-B1 slot could prevent the system from booting when RAM is inserted there.

  • CPU Memory Controller:

    The CPU’s integrated memory controller could be defective, but this is less likely given that one slot functions correctly.

  • Recommended Actions:


    Inspect the Motherboard:

    Look for any visible signs of damage or defects on the motherboard, particularly around the DIMM slots.


    Test with Different RAM:

    If possible, test the system with a different set of compatible RAM sticks to rule out any peculiar compatibility issues.


    Consult the Manufacturer:

    Since the components are under warranty, consulting the manufacturer is advisable. They can provide detailed instructions for further diagnostics, which may include testing the motherboard and CPU independently.


    Without additional components to test with, pinpointing the exact cause is challenging. However, the symptoms suggest a motherboard-related issue rather than a CPU defect. Engaging with the manufacturer for warranty service is the most practical next step, as they have the expertise and resources to diagnose and resolve such issues effectively.

    System Specifications Recap:

  • Motherboard:

    Asus B450m MK-ll

  • RAM:

    Corsair Vengeance LPX 16GB DDR4 3600 MHz (2 x 8 GB)

  • CPU:

    Ryzen 5 5600g

  • GPU:

    AMD Sapphire Nitro Plus SE RX 590

  • Power Supply:

    EVGA 600 – 100-W1-0600-K2

  • In summary, while the situation is perplexing, especially given the newness of the components and the absence of overclocking, the steps outlined above should guide you towards a resolution with the help of the manufacturer’s support.

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