Is it really dangerous to supply your risers with SATA?

Have you also heard that feeding SATA risers is dangerous and that there is a risk of fire? If you've never had a clear, reliable answer to your question, read on:

The risers currently on the market do not feed from the motherboard, they draw their 3.3v continuous supply directly from the 12v continuous supplied by the power supply. There are currently three types of ways to supply a riser: the SATA connection, the MOLEX connection and the 6 pin connection. Let's see what are the limits of these connections:

SATA POWER SUPPLY: RISK OF FIRE?

Yes, with a SATA connection there is a risk of fire, but not in all cases. SATA connectors are designed to withstand 4.5 amps (therefore, for 54 watts) on 12V DC. The PCIe specification allows a GPU to draw 5.5 amps (66-75w) from the PCIe 3.0 12V bus, therefore from the x16 riser slot. This is why many say that a riser can deliver up to 75w. So you understand that at full power, the electrical power coming from the riser exceeds the limit of the SATA cable which causes a fire hazard. 

For example, a 1080 ti GPU draws 4.4 amps at 80% power and over 4.5 amps at 100% power. Therefore, a 1080 ti at full power draws over 4.5 amps, which exceeds the limits allowed by SATA. It is therefore strongly recommended not to use SATA cables on risers that supply more power-hungry GPUs.

What about small low power GPUs? If you respect the limits mentioned above, it is possible to supply your GPUs with SATA in a safe way. However, in our opinion, it is always better not to take a chance and use either the MOLEX connector or the 6 pin connector. 

MOLEX POWER SUPPLY: THE BEST ALTERNATIVE TO SATA?

No, MOLEX is not "the best" alternative to SATA. MOLEX connectors on the market are often of poor quality, which can lead to fire hazards themselves. However, we recommend risers with an integrated MOLEX connector which are generally of better quality.

The 4 pin molex connectors are rated at 11 amps for the 12V rail, so 132 watts. So, if the connector is of quality, it is possible to supply MOLEX to the 75w of your risers. However, we still recommend using the MOLEX only if you run out of 6 pins available, so as a last resort.

THE 6 PIN POWER SUPPLY: THE KING OF CONNECTIONS?

Yes, the 6pin (18 AWG) power supply is hands down the best way to power risers. If you run out of it, the ideal is to use a server power supply that will provide you with the maximum or Dual PCI-E Splitters .

According to accepted computer standards for secure connections, 6 pin connections are rated at 75w maximum and 8 pin connections at 150w maximum. If this rule is followed there is therefore no risk of fire. However, it is not entirely correct to calculate this way. In fact, the 6pin (18 AWG) connectors are designed for a maximum of 216w on 12v, but it is better to play "safe" and not reach the allowable limit. 

Anyway, whether it's 75w or 216w, it's still enough to power all GPUs in PCIe 3.0. 

IMPORTANT: Your graphics card and its riser must be powered by the same powersupply. Otherwise, the two powersupplys will fight to supply the graphics card with 12v continuous. This can seriously damage your equipment and even cause a fire.