Computer restarts only when gaming (power supply)

When we buy a graphics card, the only thing we take into account is if the power source that we will use includes the necessary connectors for power and if the total watts is sufficient. So far everything is fine, it is a good start to combine a power source with a certain graphics card, but there is a secondary aspect, but very important that we must take into account, I will explain it a little later.

silverstone output max

1. Context of problem

I bought a graphics card that consumes around 180 watts, this one has 2 8-pin PCI connectors, everything is fine, everything works great, the power supply is 400 watts and a decent brand. The problem is that when playing after a few minutes, the computer restarts without any type of error or warning.

2. What could be causing it?

If we rule out that the graphics card is damaged, the only thing that can be left is the processor or RAM, but if we also rule out that these components are damaged, the power source remains. How do I know? The only change made was to install the graphics card, and it has already been tested correctly on other very similar systems.

3. Is it a driver problem?

I doubt it, if it were a driver problem we would have errors and some Windows blue screen of death, but instead they are instant reboots at hardware level.

4. Actual description of the problem

In simple words, the power supply does not have the necessary capacity on the +12 volt rails, which is the rail that powers the graphics cards and the processor. If we read the label of our power supply, it tells us what the limit is in amps or watts for each rail, for example, in the system that I had the problem of automatic restart the maximum amperage supported in +12v was 25 amps.

To calculate the limit in watts, I simply multiplied 25 amps by 12 volts, and the result was 300 watts. A Ryzen 5 2600 maximum consumes 65 watts (without overclocking), and an RX 580 8 GB can use 188 watts. If we add it, we will obtain an 80% (approximate) use of the capacity of that rail.

Contrary to what I mentioned above, however, the real problem was not this, although it was quite close to being the problem. This is due to the fact that the power supply had 2 6-pin PCI outputs, which combined gave 150 watts limited by the ATX specification, the 12 volt rail did support the graphics card, but the fact that the manufacturers were guided by specifications means that they have limits per connector and that even with adapters it is not enough.

5. Solution to the problem

The ideal is to buy a power supply with a greater capacity, but for people who cannot afford that luxury, with the MSI Afterburner tool we can limit the maximum amount of watts that our graphics card uses, and thus we can use it without any problem while we update our power supply.

6. Configuration used

I got this experience with a RX 580 8 GB MSI and a 400 watt SilverStone power supply, using 6-pin to 8-pin adapters, I just didn't understand why it restarted so often. If we have doubts, we can read: using a power supply smaller than the recommended one.