PCI-Express Y-Adapters

[Stealth]

Since I can't post in any support forums yet, I might as well ask a question here.

Does anyone know if using Y-Adapters for powering PCI-Express video cards is a bad thing?

I have a 1200W power supply and two HD 7590 video cards.  The power supply only seems to have 2x 6 pin connectors, and the cards require 2 each.  I have Y adapters so that I can run both cards.  Everything runs fine until I try to start mining.  At this point the computer crashes pretty much instantly.

I'm assuming this is a power consumption issue since there are no relevant events logged by the windows event viewer.  But since I have a 1200W power supply (Dell T7600) it seems unlikely that I've run out of power.... which brings me to the Y-adapters.

Thoughts?

[bitcoinmaster2]

Depending on the Operating System you use you can check for power failures.
On mac there's a tool called istatmenus, but I'm pretty sure there are also such tools available for Windows.

If it's an issue caused by the Y-Cable, the cables are too thin. But I wouldn't count on that. It could also be a software issue.

For more information you could check the log files

[Stealth]

Depending on the Operating System you use you can check for power failures.
On mac there's a tool called istatmenus, but I'm pretty sure there are also such tools available for Windows.

If it's an issue caused by the Y-Cable, the cables are too thin. But I wouldn't count on that. It could also be a software issue.

For more information you could check the log files

Well, it appears that Windows is recording a power failure... Kernel-Power.  I'm just not sure about why.  Again, 1200W power supply, brings me back to the Y-Adapters.

[aspeer]

have you checked to see how much each of the rails provides or if its a single rail PSU? possibly you're exceeding the rails supply

[Stealth]

have you checked to see how much each of the rails provides or if its a single rail PSU? possibly you're exceeding the rails supply

Sadly, Dell doesn't seem to make that info available, but it's very possible that this is the case.  The system is supposed to support 2 graphics cards, but the PSU only has 2x 8 pin and 2x 6 pin connectors available.  And I need 4x 6 pin connectors.

Here is the info that I could find.

POWER
NOTE: The T7600 utilizes an Active Power Factor Correction (APFC) power supply to enhance efficiency. Dell recommends only Universal
Power Supplies (UPS) based on Sine Wave output for APFC power supplies, not an approximation of a Sine Wave, Square Wave, or quasi-Square
Specifications
Power Supply Wattage
1300W (for AC input voltages of 181—240 Vac)
1100W (for AC input voltages of 108—180 Vac)
1000W (for AC input voltages of 100—107 Vac)
AC input Voltage Range 100 - 240 Vac
AC input current (low ac range/high AC range) 14.0 A / 7.0 A
AC input Frequency 47 Hz / 63Hz
AC holdup time (80% load) 16 MSEC
Average Efficiency (Energy Star 5.2 Compliant) 87 – 90 – 87% @ 20 – 50 – 100% load
DC parameters
+12.0v output 12VABCDEFGHIJ ; 18.0A
+5.0v auxiliary output 4.0A
-12.0v output 0.5A
Max total power 1300W
BTUs/h (based on PSU max wattage) 4113.0 BTU
Power Supply Fan 60*25mm (x2)
Compliance:
1watt requirement Yes
Climate Savers / 80Plus Compliant Yes
FEMP (CECP) Standby Power Compliant Yes

[bitcoinmaster2]

have you checked to see how much each of the rails provides or if its a single rail PSU? possibly you're exceeding the rails supply

That seems likely.

[bitcoinmaster2]

It seems as your whole power system (cable to PC) is not able to get that much power, so that voltage crashes and with it the PC. How does the PC crash appear? does it reboot?

[Stealth]

It seems as your whole power system (cable to PC) is not able to get that much power, so that voltage crashes and with it the PC. How does the PC crash appear? does it reboot?

It just goes dead and reboots, as if the power had gone out in my house and been restored.

I think my next best option is to attempt to get an adapter for the 8 pin power cables.  I've never seen an 8-pin to 6-pin adapter though.  I've seen plenty of 6-pin to 8-pins. 

An 8-pin should be able to plug into a 6-pin slot, however these connectors have extra plastic that prevents that.

[bitcoinmaster2]

It seems as your whole power system (cable to PC) is not able to get that much power, so that voltage crashes and with it the PC. How does the PC crash appear? does it reboot?

It just goes dead and reboots, as if the power had gone out in my house and been restored.

I think my next best option is to attempt to get an adapter for the 8 pin power cables.  I've never seen an 8-pin to 6-pin adapter though.  I've seen plenty of 6-pin to 8-pins. 

An 8-pin should be able to plug into a 6-pin slot, however these connectors have extra plastic that prevents that.

Okay, then it's pretty clear that the diameter of the current delivering cables is too small. Now there are two possibilities, either from the socket to PC or from the power supply to the GPUs.
I'd go with your opinion to get 8-pin cables

[Stealth]

It seems as your whole power system (cable to PC) is not able to get that much power, so that voltage crashes and with it the PC. How does the PC crash appear? does it reboot?

It just goes dead and reboots, as if the power had gone out in my house and been restored.

I think my next best option is to attempt to get an adapter for the 8 pin power cables.  I've never seen an 8-pin to 6-pin adapter though.  I've seen plenty of 6-pin to 8-pins. 

An 8-pin should be able to plug into a 6-pin slot, however these connectors have extra plastic that prevents that.

Okay, then it's pretty clear that the diameter of the current delivering cables is too small. Now there are two possibilities, either from the socket to PC or from the power supply to the GPUs.
I'd go with your opinion to get 8-pin cables

Agreed.  It just boggles my mind that a system specifically set up for multiple cards, with a very powerful power supply, doesn't have the connectors necessary.  Anyway, I'll see what I can do about harnessing the 8-pin cables.

[Rishodi]

First, are your graphics cards installed in the correct expansion slots? That system has 6 PCI-E slots. The two on the top are unusable without a 2nd CPU. Of the four on the bottom, the 2nd and 4th (from the bottom) are x4. Your cards should be in the 1st and 3rd slots from the bottom which are x16.

Second, I cannot fathom why any 1200W power supply would have only 2 PCI-E connectors, or why any system with multiple PCI-E slots would use such a power supply. But that's Dell for you.

Third, the tech sheet is unclear on DC output. Do the 10 letters mean that your power supply has 10 12V rails each capable of providing 18A? If so, that's a measly 216W per rail. Your 7950s each have a TDP of about 200W.

One possible source of the problem is the Y-adapters. I hope that each of the PCI-E connectors coming from the power supply is on its own 12V rail, but if they're on the same rail then they would easily be overloaded.

Are you trying to mine on both these cards simultaneously, or does the PC crash when you try to start mining on a single card? What happens if you uninstall a card and try to mine on the one that remains?