No, you need to test when they're plugged into the miner, measure another PCI-E. What PSU is it?
That's what I did. I'm not sure what I'm misunderstanding? They are plugged into my miner and I shoved my probe into the back of the plug where the contact is and grounded to the case. I got 12V with it running and plugged in.
LEPA ATX12V/EPS12V CrossFire Ready 80 PLUS Gold Certified Power Supply G1200-MA
http://www.amazon.com/gp/product/B00DF4RXWQ?psc=1&redirect=true&ref_=oh_aui_detailpage_o02_s00