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I picked up a second hand mobo for a good price - Asrock Fatal1ty Killer Z87 board.
It has 7 pcie slots - 3 x 16 and 4 x 1, so I thought it should be good for gpu-mining.
I got Win 7 installed with drivers and connected 2 x RX 470 cards directly into two of the x16 slots
and claymore eth miner was running fine.

As soon as I install a 3rd card in one of the pcie x 1 slots via powered riser, then upon
reboot the rig hangs with all the gpu fans spinning seemingly at max (It was quite loud). 
I know the riser is good as I was using that one in another rig.
In the BIOS there is only option to set the x16 slots to Gen 1, Gen 2 and Auto.  I had all
three set to Auto, so that didnt work.  There is no option to set the pcie 1 slots to Gen 1 as
they are already Gen 1, right?
I never got so far as to try setting the x16 slots to Gen 1. If that fails what else should I try?
The PSU is a 760Watt Corsair AX760, the kill-a-watt with two cards mining eth showed 230Watts
so power is ok.

One of the card maybe broken.

No, I have plugged the gpus back in the rig from where they came.  So they are mining away in the old rig.   
So the only thing I swapped was the mobo.
But my focus now is to get the Asrock mobo to work..

Might try flashing the bios. Side fact, I had the same problem on a Asrock P68 board, ended up trashing the board and buy a Z170 instead.

I already flashed the mobo with latest bios, 1.70.
I have set the PCIE -16 slots to Gen 1 in BIOS and am able to boot into Win 7 with all 3 cards connected,
however, OS only sees the two cards in the 16-slots, so it will only mine with those two cards. 
Any other thing I can try?

start with a riser card alone 

if the riser is good
if the card is good
if the cable is good

the card should post and allow you to plug a monitor in.

how many  1x slots do you have?

if you have more then 1 try each one at a time.

Hi Phil.
Thanks for the tips.  Yeah, I went through a few hours of trial and error.  All the ifs you mentioned were positive.
The risers, and GPUs and PSU came from another rig that is working fine.
This ASRock board has 4 pcie x1 and 3 pcie x16 slots.
Back to the problem; I powered off, removed all the GPUs, rebooted and in the BIOS selected Gen 1 for all the PCIe slots.  
Then restarted, powered off again, then plugged in one GPU in the first pcie x1 slot (first slot), and powered up.

After reboot the keyboard doesn't work, the display was showing the BIOS boot screen telling me to press F2 to enter the BIOS setup.  
I swapped for another keyboard, it, too, doesn't work.   I tried all the available USB 2.0 and 3.0 slots - no difference.  
With the 1x riser I then connected the single GPU in pcie slot 2 which is the first 16x slot, rebooted.  
Now, no display so no telling what went on, but this time I was able to toggle the keyboard caps lock and see the led for that coming on,
so apparently the keyboard was back on.
I powered off, reset the BIOS settings, then repeated all of the above with same result.
Just to check, I powered off, removed the riser and plugged the one GPU into the first 16x slot
After reboot the rig is back up and all is fine.
Can anybody explain why the keyoard doesn't work when I connect the GPU in the first 1x slot?

That motherboard sure does not sound well :( Contact manufacterer and ask if it really supports that many GPUs.

Is Power Connector 22 on the motherboard being powered by the power supply? Page 27 of the manual says, "Please connect this connector with a hard disk power connector when two graphics cards are installed on this motherboard."

Do it



I have this same board and it works with 7 gpus. In the pci express x1 slots you will have to do this:

https://www.gobitgo.com/_images/_articles/PIC-E-1X-Jumper-Wire-Step-2.jpg

Sorry for my bad English

That's interesting. Do you have any other references or documentation which explains why this works? I suppose that you have to jumper each PCIE x1 slot, right?

The documentation is here:
https://bitcointalk.org/index.php?topic=36061.0
https://bitcointalk.org/index.php?topic=102547.msg1124000#msg1124000

Ok, I found an old thread where this mobo was discussed in detail.
Looks like the clue to get the pcie x1 slots working is to short pins A1-B17 to fake the presence of gpu in the slot.

Adding the link to it here for my own reference for later build...
https://bitcointalk.org/index.php?topic=36061.140 (https://bitcointalk.org/index.php?topic=36061.140)

EDIT 20170508 It turned out that the riser I used (old ribbon cable variant) was not working with the pcie-x1 slots on this board.
I have now replaced them with the more modern USB riser variant (version 006)
and this riser works out of the box on this motherboard  ;D