USB risers vs. Ribbon risers (issue w/ a card)

[wand3r3r]

Has anyone experienced issues with USB risers on certain cards?

One card works fine (7950), the other didn't work (6950) so I tried another riser and then I even tried the riser which worked on the first card to no avail.

The 6950 works on 1x-16x ribbon powered risers but not on USB risers.

Edit:
It's due to the PSU. One card had to be on the other PSU for whatever reason. Switching two of them to the other PSU was the only way to get it working at all.

 

[Hurin]

I've seen a couple reports of AMD-based motherboards not getting along with powered USB risers. Not verified though.

 

[wand3r3r]

The MB is an Z87 MSI Gaming and the problem is that one 6950 works with a ribbon riser, but not with a USB riser (both powered by molex). The USB riser works with a 7950 so it's something to do with the 6950 apparently?

 

[oblox]

I've had issues with the usb risers on some 270s but the risers worked in a different motherboard. Beats the hell out of me. I'll continue using them though due to ease of spacing and the quality vs standard ribbon cabling.

 

[Digital Viper-X-]

my 290x mining rig has a mix of both

2 16-16x powered ribbons

1 1x-16x powered USB

You need to make sure the cable is snug with the USB ones, I found that mine wasn't in fully and it didn't work until I pushed it in a bit more. (TWSS)

 

[Lunas]

Some boards you may need the presence pins shorted.

 

[nightwalker]

Some boards you may need the presence pins shorted.

I thought the USB risers already fixed that problem?

 

[wand3r3r]

^ Yeah they are supposed to work without shorting anything.

The USB riser was not the issue.

The only way to get the MB to see the card was by switching to the primary PSU.

PrimaryPSU1
Card A1
Card A2

SecondaryPSU2
Card B1 (powered riser from PSU1)
Card B2 (powered riser from PSU1)

For whatever reason B1 had to be connected to PSU1, and A1 switched to PSU2.

Strange.

 

[_r2h]

little tip of you guys with multiple PSUs, make sure all the 5v lines on the risers run to the psu switching the mobo off and on. Otherwise if you reboot,shutdown, whatever the gpu won't reset proper and cause you all kinds of issues.

 

[Vengance_01]

Just built a 6 GPU rig using all USB risers with the asrock H81 BTC board. Not a single problem. Completely plug and play.

 

[customminer]

Just built a 6 GPU rig using all USB risers with the asrock H81 BTC board. Not a single problem. Completely plug and play.

How did you cable them up?
3 on one, 3 on the other?

I just had issues with trying to get 6*usb riser cables working - only 2 of the gpus would power on :S

 

[Mega666]

Get the right motherboard and be reasonable with your GPU count. You won't need to deal with powered risers then.

 

[customminer]

Get the right motherboard and be reasonable with your GPU count. You won't need to deal with powered risers then.

Aww, but i'm wanting to put 6 on the one 4P mobo : (

 

[collegeboy69us]

Get the right motherboard and be reasonable with your GPU count. You won't need to deal with powered risers then.

Not too many 6 slot 16X motherboards around that would be usable with non powered risers.

Even with the right PSU I wouldn't want that much power flowing around the motherboard itself.

I'm happy I got a 5 card rig stable with my 850W PSU was going to go dual PSU and try for 6 but not worth it at all.

I still have 3 GPU's sitting around useless till I piece together one more system. just need to find a cheap awesome mobo.

 

[Mega666]

It's a fine line between efficiency and power/stability. Motherboard is key along with power. I use a Tripp Lite LC2400 on every box. Has a fat torrid power store (transformer) to even out the fluctuations. You should also be looking for motherboards with lots of extra power sockets - six and/or eight pin that power the pcie bus..