Why are some risers powered and some not? (PCI Express)

[nodesupply]

Basically as the subject states.

Why are some powered (with that little molex hanging off) and some not?

Is there something about more then 3 cards in a motherboard requiring the power?

[glub0x]

same question here, how to know if we should use powerd risers?
is it risky for the MB? (if i try with 5 CG and no powerd RIser, will it burn the CG or MB?)

[mitty]

Not directly answering this question, but I'm running a machine with 3x5830 and 1x5850 all on unpowered risers (2 on 1x, 2 on 16x slots) with no problems.  I assume there isn't an issue since the cards have their own power connectors but then again I don't know for sure if this is a bad idea.

[zvs]

always use powered risers on pci-e x1 slots

other cases would be based on what cards you already have in the system & the quality of the motherboard

[Jay_Pal]

always use powered risers on pci-e x1 slots

other cases would be based on what cards you already have in the system & the quality of the motherboard

Can you please develop further?
I couldn't gather this information months ago, so, I'm running a single 5830 on an old motherboard that has a non working pci-e x16 slot, so after being unable to figure this question out, just hacked the pci-e x1 slot to accommodate the card, not using any riser.

[Zanatos666]

I think it depends on the card and if it has PCI-E power connectors from the PSU or if it gets all of its power from the slot itself.  For example, I have an unpowered riser on a 5870 and runs just fine, but it has connectors to get its power from the PSU, not from the bus itself.

[Jay_Pal]

I think it depends on the card and if it has PCI-E power connectors from the PSU or if it gets all of its power from the slot itself.  For example, I have an unpowered riser on a 5870 and runs just fine, but it has connectors to get its power from the PSU, not from the bus itself.

My 5830 has 2x6pin connectors. That could explain it! Thanks.