According to the power supply connector overuse definition from SilverStone warranty information. A single PCIe 8pin cable and connector’s maximum current rating is 12.5A, which is 150W (+12V x 12.5A). So SilverStone’s warranty will not cover damages or malfunction resulting from the use of a graphics card or expansion card with a single PCIe 8pin connector that exceeds standard 225W total power draw (150W from PCIe 8pin connector + 75W from PCIe motherboard slot). Similarly, a graphics card or expansion card with dual PCIe 8pin connectors that exceed 375W total power draw (300W from two PCIe 8pin connectors + 75W from PCIe motherboard slot) will also not be covered under warranty.
Thus, to power high consumption graphics cards (above 225W) with two or three PCIe slots, SilverStone recommends using two or three separate PCIe cables to connect such cards to the power supply.