You can try configuring the server in "Enterprise Infrastructure Planning Tool" (Link below) and check the power requirement of both the server [URL] 
In my datacenter power prices just increase 100% thinking to replace one sever. Got R6515 400Gb ram and power is around 150W to 170W + HBA and its ok Don't like big servers 2U was fan for years for 1U server thinking to get: R7515 wiht also EPYC 7452 __ So question is is power consumption will be "same around" between 1U and 2U will be same 8 SSD on front and 2 SSD on back on beginning  400RAM  + performance fans. Got one HP and sometime can hit 400W. Is 12 x 3.5 and 2 x 3.5 on back can affect air flow and fans will be eat like 50W ?
PowerEdge R7515 12 × 3,5+ 2 x 3,5" on back - power consumption