I measured the power consumption. With same core, different memory frequency (750/1500MHz (Lyra) vs 750/1000MHz(Neo)), but higher voltage (880mV vs 840mV) Lyra is about 10% more than Neo. 950W compared to 870W with Neo. That is with 4X7990. I cannot run Lyra with the same voltage as it is not stable.
my friend could run 7990 at 870/1500 ~ 1mb/s at 1.00 vcore, temp 47~52
but in Neo he should run at 1040/1500 ~ 318kh/s at 1080 vcore or higher, temp 57~65 ( at the same ambient temp with lyra)
in this case your 7990 require a lot more vcore to run stable compared with neoscrypt, but it doesnt mean that lyra eat more power
That does not prove that Lyra uses less power. Your friend uses lower voltage and frequency in Lyra.