Topic: Bitfury 400G FIRE Hazard (pics) (Read 4080 times)

Right now I am using two seprate 6pin connectors and the total system draw iw 408 to 418 watts at the wall. I am hoping this is safe. The boards are overclocked but only slightly. I could push them higher - and they were - but once again the power draw would melt the wires. I am not sure what solution would work to give the boards more power. I forget if the v2.3 m-board has any screw type power connectors. I know the new style m-boards have both though.

I guess I should mention that I'm powering the rig with a Corsair AX860.

The pictures is what's throwing you off. The cable itself is rated at 18 ga @ 90C. There's a lot mentioned in this thread that people don't understand so let me clear some things up. XFX (seasonic design) in there 850w psu line uses an 8 pin plug that plugs into the psu. They only utilize 7 pins of the 8 pin connector, but use 8 wires. The reason for this is a 6 pin and 8 pin PCI express connectors each only use 3 hot wires while the rest are all grounds. So according to pci express specifications, a 6 pin (3 power, 3 grounds) is rated for 75 watts while an 8 pin (3 power, 5 grounds) is rated for 150w watts. So this psu design is based off pci express spec should be able to push 300w through this cable with overhead. If the bitfury unit utilizes all 3 power inputs then you should be fine. Otherwise no matter what psu pushing 300+ possible watts through three 12v power lines is pushing 9 amps through 18 gauge wire and is not a good practice. The 18 ga wire should be fine to push that amperage, but the quality of terminals/connectors whether in the psu or on the wire may not be able to support this.

If the bitfury m board doesn't have the space to accommodate an extra 6 pin power, then it would have been smart to utilize the screw attachment for a 3rd set of power connectors. Oh also you can see the one psu cable melted, but the other cable was on the verge of melting too as the cable is extremely stiff and upon trying to remove the psu cable I eneded up cracking the connector as so much heat was generated it looks to have started melting and was partly fuzed.


PSU Review

http://www.legitreviews.com/xfx-pro-series-850w-black-edition-psu-review_2239/8

http://www.hardwaresecrets.com/article/XFX-PRO-850-W-Black-Edition-Full-Modular-Power-Supply-Review/1716/13

Waaat I looked yesterday & today & saw no such thing,assume your PC was compromised already & reinstall your OS ASAP  

Where did you get your screw connector from?

DONT OPEN THE PICTURES IN MAINTHREAD! THERE WHERE kid porn! I have report it to an mod.

Okay...Ive done this (routed to both the screwed connections and also to the two six pin Pcie cabled sets.

If I'm using a 700W PSU - could that cause my rig to perform lower than expected?  Should I bump it to a 1000W PSU JUST to utilize higher hashrates?  I'm lucky if I see 460-470 GH/s on 700W coolermaster

Like you say according to the AWGs they should be able to hold more - but those AWGs allow wire temps up to 80C or something rediculous. That's why 6 pin PCI-Es are rated at 75W [should really be ~150W] and 8 pin at 150W [should really be ~250-300W].

From the ASICMiner blades, I can tell you tough that plenty of things that say they are 18AWG clearly aren't and burn pretty quick.

This happened to me as well. I made the mistake of going from 8pin PCI-E to dual 6 pin on the same modular PSU cable. I now have two separate PCI-E power connectors but I still worry it may cause melting in the future. The system draws 418 watts on average now.

Tip for you guys, make sure if you overclock the boards that you a) run separate PCIe cables from your PSU b) use the thickest gauge PCI-E cables possible c) if possible run an additional 12v to the screw type power connectors on the m-board.

Speaking of which does anyone know where I can buy a pci-e 6 pin (or even molex) to the screw type connectors? (ie plus and negative 12v)

I personally think they should've used 2 x 8 pin PCIe jacks on the m-board. They knew people are going to try to overclock these and thus power consumption would be noticeably higher.

Did anyone notice on the picture of the melted cables that the ones on the top right where a thinner gauge than ones on the bottom.

How thick your wire is (gauge) determines it's the melting point / max load. It should be written on the cable.

The ones with "PSU" look very odd having two different gages and three wire on the top and four on the bottom.

Maybe it's a safety feature to stop it melting into a short, or maybe the manufacturer was cutting corners, I dunno, but the thinest wires are determine the max load on this cable and it's not as good as the cable on the far right with nothing written on it where both the top and bottom wires are the same gauge.

http://en.wikipedia.org/wiki/American_wire_gauge

Ok, i want to say again... I've used seperate PCI-E cables before and yet the plugs on the cables have melted on the inside of my modular power supply.  Yes they were absolutely plugged in tightly..they click in.

With that said Cables CAN still melt even if they are both separately plugged in.  I've had it happen to me on a 7990 Malta before.

My conclusion is not all power supply manufacturers make the same  PCI-E cables and thus they can only take a certain amount of watts / current through them.
For reference this happened on a 7990 malta video card and a Seasonic Gold modular 850 watt supply.

Bad power PCI-E cables CAN cause the melt.

It's also a good idea to never load a connector/outlet more than 80% of what its rated for 24/7 use. This can be seen in the US national electric code in numerous areas. It goes into detail in NEC Table 210.21

For a heads up, all my rigs use separate 6 pin pci-e power cords. You can see from my pictures that there are 2 psu cords plugged into that XFX 850. I didn't use one cable with 2 6 pin pci-e ends being that would be 550w through 18 ga wire which you'd fry in no time.

Here's a decent chart for current capacities of AWG sizes 

http://www.powerstream.com/Wire_Size.htm

Learn it,live it.......or burn it 

Get male connectors from here,add the pins though,not auto included:

6pin:
http://www.frozencpu.com/products/8620/ele-361/FrozenCPU_ConnectRight_6-pin_Male_PCI-Express_Power_Connector_-_Black.html?tl=g51c385s1005

8pin:
http://www.frozencpu.com/products/8693/ele-369/PCI-E_8-pin_Male_Power_Connector_-_Black.html?tl=g51c383s1007

Contacts (e.g. pins) have a current rating as well, which is independent from the capacity of the wire.

Hi Punin, as I'm sure you know, 13A/pin is dependant on the type (and quality) of the pin used in the housing. I think it's quite possible, even likely, that the contacts used in the PSU adapters are the culprit, at least in my case.

+1

Or just solder big fat wires directly to the board and the PSU bypassing any connections that might cause you trouble.

Though I doubt that there would be any point in using a overpowered PSU other than efficiency. Any good quality power supply can handle full load (though I would modify them to spin their fans at full speed all the time instead of the "silent" nonsense). If you buy a low quality power supply, it can just blow up (shorting the outlet) because it uses active PFC and the primary cap dies (I have repaired one such PSU and have ordered parts to repair another).

Well, each 6 pin has 3x 18 gauge awg 12v + ins, which should hold 10 or 11 amps each in theory. That means a max wattage of 360 - 400w each, but you get pretty close to the max at 600w load. If the psu cheaps out and uses 20 or 22 gauge awg you will probably run into problems.

This is PCIe spec, not molex.