Keep in mind that - in all likelihood - the ASIC driving those ports is the same ASIC. It's typical to have 4 ports to an ASIC on gigabit switches. @mythosmc if you've ever tried to apply QoS on four ports of a Layer 3 switch and seen it apply to three others, that's why.Ok, I'm out of ideas
Just for the sake of completeness: mgmt port is connected directly to the CPU, it is not part of the switched ports... maybe it causes some delay? I've onestly not tryed it yet... I might give it a shot tomorrow (now in Italy it's 1:30 AM...) on my 6450 24P, basically because now I'm curious
In any case, it doesn't explain why when you shut those ports the latencies go down...
If I had to guess, I'd say that the ASIC on those four ports is bad and it's causing issues, possibly flooding the TCAM with garbage. If you enable those ports, ping the switch, then disable them and check the logs (show log), what are you seeing between the port enable and disable?
It's entirely possible too that whatever fried the PoE board on that switch came through one of those four ports, and managed to kill the ASIC at the same time.