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Topic: FS: PCI-Express Extender Cables(w/ Molex)*GPU Dummy Plugs*PSU Adapters - page 16. (Read 83072 times)

legendary
Activity: 1855
Merit: 1016
I understand you saying common ground.
I am asking, is my above setup will be safe?, coz besides ground, it may rise some other problem, that why asking.
legendary
Activity: 3920
Merit: 2349
Eadem mutata resurgo
Quote
just make sure all your grounds are common

that's what I said .... read slower maybe?
legendary
Activity: 1855
Merit: 1016
Ground is going through the PCIe bus. Pins A2+A3;B1+B2+B3 are the 12v pins rewired to the Molex. Regarding GPU detection using these cables on a 5970 or 6990 would detect without further wiring modifications.

Trentbz/Inaba, http://blog.zorinaq.com/?e=44 Per the reference posted in this blog and confirmed test current drops from a combined 14A to < 1A. Preventing cable wear from extended use. Let me know if any questions.

Thanks for the link, but I don't see where it's saying he was using two power supplies with independent ground potential.  From the way the blog reads, he's connecting the +12v to the same PSU that is supplying power to the motherboard, making the ground the same regardless of the +12v source.

If my +12v source is coming from a different PSU than is grounding the motherboard, the potential will be different and that's where the bad things can start.  I completely agree that there would be no problem supplying +12v from a molex on the same PSU that's grounding the motherboard.


Yes, best if used off the same PSU. Also if using multiple PSUs just make sure all your grounds are common. What crazy set-up would have two PSU's right next too each other, supplying the same equipment with 'floating' grounds? You are asking for trouble if that is your case anyway.

Whole server farms make sure that the ground is common throughout the building. If you want to have floating grounds that is your own problem I'd say. The basic idea is to bypass power around mobo to PCIe GPU card, ATX PSU connectors have reported burnouts with more than 3 5970's on same mobo.

"all your grounds are come"  what does it exactly mean?

In my house their is a ground given by inserting a 1 inch GI pipe in to earth for around 2 feet & a wire is connected to that, that wires goes to every electrical  board in my house & connect to central big connector in a 3 pin connector.
Is that you saying to have common ground?

Today, i have to run 2 systems with one pc has one 6870 & other has one 5870.
I have only one cooler master GX 550W power supply & 2 low cost PSU which comes with cabinets.
I thought of connecting the low cost psu to motherboard & give power to system.
Then short the pin of GX 550 W PSU mother board connector 20 + 4 pin (Don't know which 2 pins/connections to short), which will switch on the GX 550 W PSU.
& then connecting(only after switching off 550 W PSU & computer) PCI-e 6 pins connectors from GX 550W PSU to the cards in 2 separate pc, the 6870 & 5870.

Can it be done & is it safe to do it?
I won't run this setup for months. It is just for 3-7 days, until i get Cooler master silent pro gold 1200 W. Its in shipment & i don't want my newly bought 5870 card lying around.
legendary
Activity: 3920
Merit: 2349
Eadem mutata resurgo
Ground is going through the PCIe bus. Pins A2+A3;B1+B2+B3 are the 12v pins rewired to the Molex. Regarding GPU detection using these cables on a 5970 or 6990 would detect without further wiring modifications.

Trentbz/Inaba, http://blog.zorinaq.com/?e=44 Per the reference posted in this blog and confirmed test current drops from a combined 14A to < 1A. Preventing cable wear from extended use. Let me know if any questions.

Thanks for the link, but I don't see where it's saying he was using two power supplies with independent ground potential.  From the way the blog reads, he's connecting the +12v to the same PSU that is supplying power to the motherboard, making the ground the same regardless of the +12v source.

If my +12v source is coming from a different PSU than is grounding the motherboard, the potential will be different and that's where the bad things can start.  I completely agree that there would be no problem supplying +12v from a molex on the same PSU that's grounding the motherboard.


Yes, best if used off the same PSU. Also if using multiple PSUs just make sure all your grounds are common. What crazy set-up would have two PSU's right next too each other, supplying the same equipment with 'floating' grounds? You are asking for trouble if that is your case anyway.

Whole server farms make sure that the ground is common throughout the building. If you want to have floating grounds that is your own problem I'd say. The basic idea is to bypass power around mobo to PCIe GPU card, ATX PSU connectors have reported burnouts with more than 3 5970's on same mobo.
sr. member
Activity: 406
Merit: 251
I believe mrb is using dual PSUs as listed at http://blog.zorinaq.com/?e=42.

Quote
First PSU to power the four 8-pin connectors:
4 * 11.4 (8-pin) = 45.6 Amp
Second PSU to power everything else (four 6-pin connectors + four cards via PCIe slot + ATX connectors for mobo/CPU):
4 * 6.7 (6-pin) + 4 * 3.7 (slot) + ~3 (mobo/CPU) = ~45 Amp

I can't determine by his post how he has ground connected between them except that supplying the PCIe 8-pin via PSU #1 and supplying the PCIe 6-pin + PCIe slot via PSU #2 should tie them together sufficiently...not sure if this was intentional or not though.

I am not yet providing 12V to the PCIe slot via an extender but I did do dual PSUs yesterday and when I supplied PCIe 6-pin from PSU #2 to GPUs and PCIe slot/ATX/peripherals via PSU #1 I could not get GPUs to light up. As soon as I cross connected the PSUs via PSON and GND the GPUs lit up as expected.

I would suspect that you may have issues if you provide PCIe 12V and/or PCIe 6/8-pin from a secondary PSU that is NOT common ground with primary PSU. I know I did with providing PCIe 6-pin separate than PCIe slot 12V.

And fortunately, I didn't kill any GPUs during my 30 second power up. Smiley
legendary
Activity: 1260
Merit: 1000
Ground is going through the PCIe bus. Pins A2+A3;B1+B2+B3 are the 12v pins rewired to the Molex. Regarding GPU detection using these cables on a 5970 or 6990 would detect without further wiring modifications.

Trentbz/Inaba, http://blog.zorinaq.com/?e=44 Per the reference posted in this blog and confirmed test current drops from a combined 14A to < 1A. Preventing cable wear from extended use. Let me know if any questions.

Thanks for the link, but I don't see where it's saying he was using two power supplies with independent ground potential.  From the way the blog reads, he's connecting the +12v to the same PSU that is supplying power to the motherboard, making the ground the same regardless of the +12v source.

If my +12v source is coming from a different PSU than is grounding the motherboard, the potential will be different and that's where the bad things can start.  I completely agree that there would be no problem supplying +12v from a molex on the same PSU that's grounding the motherboard.
sr. member
Activity: 302
Merit: 250
Ground is going through the PCIe bus. Pins A2+A3;B1+B2+B3 are the 12v pins rewired to the Molex. Regarding GPU detection using these cables on a 5970 or 6990 would detect without further wiring modifications.

Trentbz/Inaba, http://blog.zorinaq.com/?e=44 Per the reference posted in this blog and confirmed test current drops from a combined 14A to < 1A. Preventing cable wear from extended use. Let me know if any questions.
sr. member
Activity: 406
Merit: 251
This may be an issue although I cannot definitively confirm as I haven't modified PCIe extenders to peel off the 12V to test yet....will do so in coming days.

However I did work on multiple PSU arrangements yesterday where one is powering board/peripherals and a GPU or two and a secondary ATX PSU powers additional GPUs. This arrangement works but grounds must be connected between PSUs. It may be something specific to my particular PSUs but I found it was not enough to light up a GPU by just making PSU #2 hot with PSON. I had to connect PSON + GND to PSU #1 and I was then able to light up additional GPUs.

I also wonder about how a GPU will light up if PCIe +12 but not GND is supplied from a secondary PSU/source. I believe forum user mrb has experience in this area, maybe he can provide some insight if he runs across this thread.
legendary
Activity: 1260
Merit: 1000
I got my order of extenders today.  However, I have a question/concern.  I'm not terribly knowledgeable about the PCIe pin package, so forgive me... but only the +12v connection on the PCIe bus is connected to these via the MOLEX.  That would seem to me it's allowing the ground to go through the bus on the motherboard.

If I were to power one of my cards with a PSU that is NOT powering the motherboard, it's going to create a ground differential that may burn out the card, the motherboard or both.  Can someone explain why this is not an issue?  Or are the cards taking their 75v from the PCIe bus not grounded through the bus?  I'm thinking they have to be, since you can put cards in a machine that do not have external power requirements and supply solely off of the bus. 
member
Activity: 112
Merit: 10
This looks like a good idea.

I am bookmarking this, as it looks like a good upgrade when I'm ready to add a second mining GPU.
sr. member
Activity: 302
Merit: 250
The slot adapter cable is to fit a larger card. So, for example, if you have a 5870 to connect, but only a 1x slot free, you could use this adapted cable with the side cut off the socket to fit a larger card.

This will suit for any card and you would use the Molex modified one for mainly 5970's or 6990 cards.

Shipping time will depend on the chosen method of shipping, however shipping is still available on International packages via First Class, Priority, or Express.
legendary
Activity: 1855
Merit: 1016
PCI-Express PCIe 1x Riser Card Flexible Extender Cable
PCIe 1x to 16x Adapter Modified Riser Extender Cable
PCIe 1x to 16x Adapter Modified Riser Extender Cable w/ Molex Connector

What is the different between the above three? Do i need it for 5870 cards, if i want to put 8* 5870 cards which has 8 slots(4 x16 or x8  & 4 x1 ) or any combination, but has 8 pcie slots.

I understand 1x cable , just gives lengthy cable so that card can be placed at a distance.
You attached molex connector, so it won't try to draw power from pcie slot.
But what is 1x to 16X modified extender cable? I don't understand & why this type of cable needed. Do it may need for 5870?

How many days approximately it will take to reach to Tamilnadu, India after i paid & you received money.
sr. member
Activity: 302
Merit: 250
Thanks, links corrected.
legendary
Activity: 1855
Merit: 1016
Update front page of this thread with changed address.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=150601570961&ssPageName=STRK:MESELX:IT#ht_791wt_1139

This address is used for 3 different products.
sr. member
Activity: 302
Merit: 250
Pictures are now posted of the Molex modified cables.
sr. member
Activity: 302
Merit: 250
If there's anyone I've yet to speak with this evening please drop me an e-mail ([email protected]) or pm.
sr. member
Activity: 302
Merit: 250
If i want to run 4* 5870, then i can go for a mother board with 2 pci ex16 or 8 slot & 2 pci x1 slot?


Yep.
legendary
Activity: 1540
Merit: 1002
Have you shipped internationally to anyone? Just to be safe.

To me in Portugal. And it was pretty damn quick to arrive too Smiley
full member
Activity: 193
Merit: 100
Have you shipped internationally to anyone? Just to be safe.
legendary
Activity: 1666
Merit: 1000
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