AMD does not actually "lie" about the wattage. The power usage reported is only for the *GPU*. VRAM + other stuff is on top of that.

Nvidia gives (at least tries to) power usage for total board if I have understood correctly.

I have two NITRO+ AMD Radeon™ RX 6600 XT cards (11309-01-20G), testing now with NBMiner. After 2 hours no rejected/invalid shares so far.

Phoenix Miner 5.6d - Release build works also but gets lot of stale/invalid shares (for example during 11h46min 4314/460/155)

Driver 27.20.22023.1004 (non-whql-radeon-software-adrenalin-2020-21.8.1-win10-64bit-aug10)
W10P version 21H1 (19043.1165)

[17:23:14] INFO - ================ [nbminer v39.0] Summary 2021-08-15 17:23:14 ================
[17:23:14] INFO - |ID|Device|Hashrate|Accept|Reject|Inv|Powr|Temp|Fan|CClk|GMClk|MUtl|Eff/Watt|
[17:23:14] INFO - | 0|6600xt| 32.37 M|   386|     0|  0|  64|  63| 33|1311| 2238|  45| 505.8 K|
[17:23:14] INFO - | 1|6600xt| 32.38 M|   385|     0|  0|  62|  51| 33|1308| 2238|  45| 522.2 K|
[17:23:14] INFO - |------------------+------+------+---+----+---------------------------------|
[17:23:14] INFO - |    Total: 64.75 M|   771|     0|  0| 126| Uptime:  0D 02:12:01   CPU:  7% |

This two card rig has total power from the wall about 210W. (85+ PSU, 230V)

Rig without cards consumes about 35W on idle desktop (Windows 10 Pro).

So total power per card is (210-35)/2 = 87.5W for ~ 32MHs on the wall with this PSU (Chieftec CTG-750C)

(GPU power is 64W & 62W, 64W card is getting hot air from the 62W card backplate, Gigabyte mATX board GA-A75M-UD2H)

(maybe a bit lower than 87.5W as CPU usage is a bit higher during mining vs. idle desktop)

Settings during this test so far with Afterburner:

GPU: 1330MHz
MEM: 2250MHz

No other tweaks tested yet.