My r7 370 is not working with 2 pci-e extensions

[popa.viorel87]

My sapphire r7 370 4gb ddr5 is not working with 2 pci-e extensions (25 cm each) but my old card hd5770 1gb ddr5 is working fine with these 2 extensions together , if I connect the r7 with only one pci-e extensions , is working fine and the benchmarks are good , I tested every extension with the r7 and both are working fine , but together are not working , the pc is open and running ( i have sound ) but the monitor is black, What is the problem ? Thank you

 

[RememberThe5th]

If they are not Powered, no Wonder....
Every cable has voltage drop, for instance on copper cable of lenght of 1m drops (by imaginary) 0.1V of 12.00V resulting 11.90V.
Why you need to use that?

 

[popa.viorel87]

hello , thank you for your reply, i want to make a wall mount pc , if my extensions has voltage drop , why my hd5770 is working fine with both extensions and my r7 is not ? i don't understand :-s

 

[RememberThe5th]

Hmm I might be wrong.
The HD 5770 requires extra power connector right? Same as R7 370?

 

[popa.viorel87]

yes same 6 pins connector .

 

[RememberThe5th]

I can say from pure guess, dont take me for word. I think personally that you need powered pcie, they get with molex connector and you can "probably" use up to 4-5 meters, but thats from guess, Dunno why it doesnt work, since I only used PCIE x1 to 16 riser via USB cable of 15 cm.
If you can get cheap on hands powered 25cm and rest with passive and test out.
Im not quite sure since neither i tried, nor nobody responds here....
But I get your idea what you want to do, as I wanted to buy that stand onto my desk (Home made, which was on sale).

And ofc. you can wait for others to answer, also I suggest you to ask on Techpowerup, they are quite fast with answers.

 

[popa.viorel87]

Thank you Robert , i posted there , hope to get support there