In my opinion each new asic part should get new warranty, but considering how shady asic manufacturers are it's unlikely. I think it follows the S/N of each miner.
For Bitmain asics PSUs are under a longer warranty. I've never dealt with a warranty where a replacement component has failed so I could be wrong.
Iceriver doesn't have any warranty on the PSU on most units, only a select few serial-numbers.
And the failure rate of Iceriver asics is much higher than Bitmain's at least in my experience handling a lot of units. Iceriver might just of had a bad batch, but that's a shame for the buyer that has to buy a new one as it's often not covered under any warranty.
Iceriver operate with + - of 10%. This is also the case for power draw.
I have a KS5L 12T doing 10Ths and pulling 3800W+ and Iceriver is refusing to do anything about it.
Bitmain on the other hand is much better and operate with 3% and they are very helpful when it comes to warranty. Most Iceriver PSUs comes with 0 warranty as well while Bitmain is 1 year.
Also any legit supplier will do a video call and show you the warehouse. Unless they think you are wasting their time of course.
Every serious supplier provides S/N and picture of the asic before it ships out. By picture of asic I mean the box. Unless its used. A lot of suppliers sends out units with expired warranty thats not good. So you have to watch out for that.