The total power consumption of your 5070Ti directly depends on the voltages at which it operates. For example, I’ve had five GPUs from the 5000 series: two 5090s, one 5080, and two 5070Tis, and none of them ran at the same stock voltages. They can range from around 995 mV to over 1.070 V, and within that range, power consumption can increase significantly in certain scenarios, such as highly demanding 4K gaming or synthetic benchmarks like Port Royal, etc.
Judging by your comment, I’d assume that your 5070Ti runs at lower stock voltages than mine. My 5070Ti operates at 1.050 V by default, and with overvolting it goes up to 1.070 V. At those voltages, and running close to 3400 MHz on the core and 2125 MHz on the memory, you definitely need 400W, or even more, to keep it stable.
These are my Steel Nomad scores with 400W
DX12 API
Intel Core i9 processor 14900KF, NVIDIA GeForce RTX 5070 Ti x 1, 32768 MB, 64-bit Windows 11}
www.3dmark.com
VULKAN API
Intel Core i9 processor 14900KF, NVIDIA GeForce RTX 5070 Ti x 1, 32768 MB, 64-bit Windows 11}
www.3dmark.com