I can't be that "lucky"
You're not lucky, you're failing to measure it correctly.
The chips run 300w or so each stock; how do you think you're getting from 220v AC to 0.7v DC with 220w/<15% total loss? Fairy dust and magic beans?
u27
https://bitcointalk.org/index.php?topic=170332.msg8071091#msg8071091
Yeah yeah, the pool is wrong, the GUI is wrong, and the Kill-o-watt reader is all wrong 'cause you said so.
..SNIP..
I'd guess your VAC is really 231 @ miner not 220.
You neglected to show ASIC total Watts in pic.
Still good numbers, 3.42T is best possible @ 475.
AND/OR
The current clamps have a % accuracy in their specs.
Worst case is low end and 15A is low end for a typical 200-600A clamp.
Unless you have calibrated yours and know,
go with worst case and add that % to total for safety.
The VRM's have an accuracy spec also.
+ or - 2.5A per VRM @ 1.0 VDC output
(spec is @0-40A, no claim made for 50A conditions on 40A part)
http://archive.ericsson.net/service/internet/picov/get?DocNo=28701-EN/LZT146435&Lang=EN&HighestFree=Y
Bottom of page 7.
So ALL numbers from miner are just ballpark.
If it were linear, 475MHz is 5% below 500MHz.
285W is 5% below 300W, you are (x)W higher ~290.
That is the price for hot VRMs IMneverHO!
Unless the ASIC is more 'efficient' @ 500 than 475.
Stranger things HAVE happened but not often.
Just like the LM75 issue, not perfect status reporting but they run!
YMMV