If your card indeed had a TDP value of 175, it's likely that max power target would be 100% + (225-175)/175 * 100, or 128% maximum power target. In the scenario I described, it's likely that whatever % value you have available over 100% is going to reflect the difference between TDP and 'max safe wattage draw', based on the connectors running to your card. Raising the Power Target up simply allows for your card to draw more juice through it's three connectors without resorting to downclocking/volting.

So, when your power limit is set at 100%, this means your card is 'limited' to it's TDP, and if whatEVER you're doing with the card is causes it to exceed a draw of 175W, the driver will start to downclock and downvolt the card in order to get it run within the expected power envelope designated by the power target slider and the TDP. Lets call that wattage amount the card's TDP, for the sake of simplicity.

However, they likely 'expect' a card with this connector configuration to draw something like 175W. The max 'rated' wattage draw from each of these three connections is 75W, and you have 3, so the absolute max wattage draw that AMD is going to 'allow' your card to draw is 225W. Let's say you have 2 x 6 -pin connectors on your card + the power from the motherboard. Your card has some amount of 'juice' it's expected to run at, at a maximum. It's something more akin to 'wattage control'. Click to expand.It's quite different from voltage control.

See ghz of processor msi afterburne