6GPU rig unstable boot.

[ravetrader]

Hey guys, i have the following problim:

Im trying to set up a 6GPU mining rig.

The problem is, that the system wont start stable. Sometimes it boots and works fine, but sometimes not.

I could setup up to 4 GPUs at once now and I could even mine with them until the first reboot. Then the system wont boot. Rebooting 4-5 times solves the problem for the first, it boot and works fine, but with the next reebot the same problem.

Im using:

ASROCK z77Extreme9
6x GPU 7970 XFX
intel CPU 2,9ghz dualcore pentium
4GB RAM 1333 kingstone
2 x PSU 850 WATT Thermaltake
6 unpowered risers
BAMT vers 1.2

someone any gues what it could be?

The problem seems to be gone if i set up the 4 GPU without risers??? Could it be the Riser? How can i fix it?

sorry for posting here, dont have the permission to post anywhere else. And sorry for bad english.

[fruor]

are the risers all pcie x1 to x16? i will setup mine these days, ordered 1 non-powered x16-x16 riser and several powered x1-x16 risers.

at first i thought it must be some power issue, yes.
can you describe "not booting" more precisely?

[sterins]

Just out of curiosity how much $$$$ did you drop on that rig?

[ravetrader]

@ hieroglyph: thank, feel free to move this where ever you think its belong to (board/mining?) but only if i still can post there afterwards

@fruor

The Risers are 16x16 all not powered. What we suggest is, that the Risers could produce some interferences, so if you use more than one at once, they kind of  troublemaking eachother, what we will try is to put them into some isolation out of aluminium foil.

One Card witout Riser works just fine. 4 Worked fine as well, as i can tell so far.

The exact trouble is difficult to discribe. It start but there are exactly 3 problems:

1 the Monitor gets no signal but seems to boot into bios.
2 no boot at all. (this one is the often)
3 boot in bios but cant boot into BAMT or detect all cards.

what i can tell so far is, dont use the 16x16. 16x to 1x should work as well even on the 16x slot on the motherboard. but they should be much better in handling and they would use less space. But i have no 16x to 1x but that is what i suggest.


@sterins

the price was in euro should be 2k-3k

[fruor]

thanks man I will only use the x1 to x16 risers then. They are all powered though. Will tell you if I run into troubles

[CaptainBeck]

How many cards can you run with before it wont boot??

[nahallacman]

I believe that it is an issue with using 16x-16x risers. I believe you can only use those risers on the 16x slots. I didn't spend the time to look up the board but my assumption is that it doesn't have 6 16x pcie slots. You should be using 1x-16x risers on any of the basic 1x pci slots (the generic white or black ones usually). There may also need to be some pins that need to be jumped on your motherboard to make 1x-16x risers work. In addition, powered risers should be used to make the power draw through the board be less. The more power that you drive through the board the more likely it is that it will wear out faster. Try putting just the slots that fit a normal 16x card with the risers and try that. If that doesn't work it is a problem with the risers themselves. If that does work, see if it happens when you a riser on just the 1x pcie slot. If the cards work just fine with the risers and it only stops when you have that many cards running you may have a power issue.
Hope this helps.

[Flashman]

You could take some load off it by downclocking the CPU as much as possible.

Unless you're using reaper, very little CPU time is needed, I had an AMD64 rig running at 600Mhz, hashed at 550Kh whether I had it at that or 2.4Ghz.

[fruor]

4+ GPUs with non-powered risers is too much for almost any Motherboard. The PCIe slot pulls 30+ W for each card, and people reported melted PCIe slots when running on non-powered risers only.