The maximum read/write speeds are around 1500 MBps for your model.
The Intel 660p is based on QLC, which can bring the read/write benchmarking speeds down and for the 512 GB these speeds are even worse than the speeds for the 1 and 2 TB versions.
In the Link below, there is a review of the 2TB version, but a comparative table with speeds:
Intel's SSD 660p marks the debut of QLC flash for the consumer market. We review the new flash brings SATA-like pricing to the NVMe segment.
www.tomshardware.com