GPU TDP and Voltage Reg.

[TrevG]

Hi, I recently built my desktop, and had a few problems getting the bios to come up, after replacing the PSU that seems to be fixed.

However under heavy load (Rendering using Blender) GPU-z indicates that my GTX 760 is only running at about 50% TDP due to Voltage reliability and operating voltage.

When I run Furmark on the 760 it runs at 100% TDP no problem, however during rendering, when the CPU is also running under load, and the other smaller graphics card is also under full load the 760 only runs at 50% TDP.

However the clocks and everything else seem normal. Is the GPU throttling?

My Specs are:
i7 4770
Gigabyte Z87-HD3
Seagate 2TB HDD
Gainward GTX 760
Gigabyte GT 610
CoolerPower 950W PSU, rated to 34A on 4 12V rails.

Everything is new, the PSU is rated to easily take the load, how do I tell if it is the PSU?

Thanks.

Edit: I tested the voltages with a multimeter, and *all the 12V rails drop from 12.33V to 12.1V under load.
* they all drop pretty much the same. I don't actually think they are independent rails.

 

[Emerald]

does it use 100% if you would take out the GT610?

 

[TrevG]

does it use 100% if you would take out the GT610?

Sorry I am new here, I only found the reply button after posting below.
No it doesn't reach 100%, maybe a slight increase in TDP and slightly less voltage drop. But nothing I would call conclusive.

 

[Emerald]

is the GTX 760 plugged into the PCIe 3.0 slot?

 

[TrevG]

Yes. GPU-Z detects it as being on the PCIe 3.0 slot running at x16.