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