The truth is Hawkfish, myself, and MintCell are all selling the same risers.
Typically we're running less than 1% defective rate UNLESS something happens during shipping to damage them. Or someone gets a bad batch. Or quality from a vendor goes downhill. Notice how none of us sell "black" risers any more. They're rubbish. The build quality went really down hill so we all quit selling them.
A few things about risers and debugging them.
You did a great job by plugging in the cards direct to the mobo to test.
I'd also suggest using another spare riser to test but most new miners don't have a spare. (or start with 1 riser and see if that works.)
Don't plug in more than 1 riser per SATA power cable. Just because a SATA power cable has 3 or 4 ports on it doesn't mean you should plug 3 or 4 risers in. If you do you will overload it. A SATA connection for a harddrive uses much less power than a PCIe riser. Many people run 2 pcie risers per cable. That may work fine for you but I suggest 1 per cable if you can. You definitely don't want to try and chain 3 or 4 risers on one SATA cable. They won't be able to get enough power.
If you have the new blue (what I call server quality risers) then they can take the 6 pin PCIe power directly.
Double check your setup. Make sure everything is connected properly. Check that you put the little 1x card in the slot properly. Check that it isn't too loose. Check your USB, SATA, power etc. When the rig is on check by touching the cables with your hands especially your molex/sata power. Make sure it isn't hot to the touch. That is definitely a bad sign.
Depending on your setup you may also need to change some BIOS settings. Typically your motherboard BIOS is set to AUTO PCIe settings, but sometimes you need to change this to "gen 1" or "gen 2". That also may depend on whether or not you're running Windows or Ubuntu. Try those too.
Finally, do you have enough power to run everything? Your PSU should run only at 80-90% capacity. Meaning if you have a 850 watt power supply you really want to run at 700-750 watts. You don't want to try and push it to 850 or 900 like some people do. That may work short term but won't work long term. Also if you're at say 820 solo mining and suddenly switch to dual mining... or make the intensity a lot higher... you can overload a power supply that ran fine for a long time.
A lot of people test their power with software tools that don't properly show the actual watt usage of the entire PC. I recommend using a kilowatt meter or amp meter. You plug the rig into this and plug this into the wall. Then you can tell the actual amount of power draw at the wall. Otherwise you're just guessing! Right now my GPUz says this 280x on this computer is using 44 watts but I know in reality it's probably closer to 200watts. Just for the GPU. Not counting everything else in the computer drawing power.
Don't get me wrong. Bad risers do happen. But there is a lot of testing you can do before you get a replacement riser.
