The discount depends on the chip, it ranges from around 6 to 16 percent. It's unknown how long this offer will last.
Earlier this year AMD already slashed official prices of its Ryzen processors in order to better compete against Intel products. That price-cut was global and had an effect on all Ryzen SKUs, but only on one Threadripper model. By contrast, this time select retailers offer discounts on select Ryzen and two higher-end Ryzen Threadripper CPUs, so evidently AMD is trying to address the higher-end of the market with its discounts.
Via: AnandTech