MSI Z77A-G45 only recognizes 4 amd 7950 cards no more

[dirtriderdan]

I have a new MSI Z77A-G45 motherboard and 7 new HIS 7950 gpus. Brand new windows 7 x64 ultimate installation. Running AMD 13.3 beta drivers and AMD APP SDK 2.8 but tried 13.1 and 12.8 as well. Attaching cards with x16 to x1 adapters. On more than 4 cards I splice the adapters to molex for power. Using dual XFX 850 psu. This setup is for litecoin mining.

My issue is I never get more than 4 cards to be recognized. Has nothing to do with what adapters I use for power. I have tried the vga to dvi dummy plug and it makes no difference. I have tried the crossfire adapters and that makes no difference. When trying different catalyst version I tried both the AMD Catalyst Un-install Utility and atiman uninstaller 6.3.1.

Anyone have any ideas? Only other thing I've seen like it is this thread and I have the exact same problem. http://devgurus.amd.com/thread/159653

[kqpahv]

Hi

Have the same board and I was also having issues with it. Still havent tried more then 3 cards yet because I am waiting form my pcie 1x-16x adapters. I am already really disappointed in this motherboard as it didnt even recognise 3 cards when 2 of them were connected in the pcie 16x slots and on in the 1x slot. Definately disable PCIE gen3 from the bios ! should leave more bandwith to share for the slots. Will let you know how I go when i get my adapters.

PS: I'v read from this forum that people are runnings rigs with this motherboard and 6 cards connected to them.

[rascal777]

Im Dealing with this exact issue now....  I got the MSI Z77A-G45   and 6 Gigabyte GV-R795WF3-3GD cards.... And now I can only get 4 cards to work with Windows 7 Home Premium and amd Catalyst 13.5 beta... I'm still working this though, and hopefully I get it.  I got this motherboard because other people have said they were successful with it.

Successful Report #1 -  https://bitcointalk.org/index.php?topic=97154.0
Successful Report #2 -  https://bitcointalk.org/index.php?topic=186877.20
Here is a Link discussing this issue

https://bitcointalk.org/index.php?topic=193695.0



My Problem is that in Windows 7 6 7950's show up, but 2 of them are disabled with Error 43.


Successful Ways to Mine 6 HD 7000 series cards with similar Motherboards

6 card setup with the MSI Z77A-GD55   and the Asus P8Z77-V Deluxe  Motherboards:

https://50btc.com/article/bitcoin_hardware_mining


So I was successful in getting 6 Cards installed using the Solution of moving to Windows 8,  however now CGminer crashes on startup

Going to try this:

https://bitcointalk.org/index.php?topic=197927.msg2062821#msg2062821

[rascal777]

This Reply is a Reference for later and is good information:
Whether or not powered risers are needed for Radeon HD 7900 series miners.

What I took from this was that they most likely are not needed for bitcoin mining, and the jury is still out for litecoin mining.


Info Pulled From this Thread.

https://bitcointalk.org/index.php?topic=199706.msg2082941#msg2082941

Time to clear up the many wrong statements that people are making in this thread. I am the person who made the first powered PCIe extender and who documented why this is necessary: http://blog.zorinaq.com/?e=44

Firstly, the current drawn through the PCIe slot vary a lot depending on the card. Dual-GPU cards usually draw more than single-GPU ones (contrary to what someone said). Here are some of my own measurements with a clamp meter around the 12V lines of a PCIe extender, while Bitcoin mining:

HD 6990: 4.2 A
HD 5970: 4.1 A
HD 5870: 3.2 A
HD 6950: 2.5 A
HD 7970: 0.9 A

So for example the 7970 (and probably most other 7xxx series cards, but I have not tested them) draws so little power that they pretty much don't need powered extenders.

Also, eroxors, most of your cards are pretty low-end/mid-end. They likely all draw less than 3 Amp or so because your most power-consuming one seems to be the HD 5870 (3.2 A through the slot). Even if you had 4 of these cards, that's only 12.8 Amp total, so only 6.4 Amp per 12V wire of your 24-pin ATX adapter.

But most importantly, whether the 24-pin ATX connector overheats or not depends a lot on whether the Molex Mini-Fit Jr. pins in the PSU 24-pin plug have a single or double spring. You can tell by removing the pin from the plastic housing and seeing if it has one or two pairs of "dots" at the end. This one has two: http://www.alliedelec.com/images/products/Small/70090646.jpg The single spring pins (typically used by inexpensive PSUs) have a higher (edit: electrical) resistance and are more prone to causing the connector to burn out over time.

For example, in my farm of 4x5970 and 3x6990 machines from the old days, I noticed that upgrading from single-spring pins to double-spring pins pretty much made powered extenders unnecessary.

Finally, eroxors, you are right that the memory subsystem of Radeon cards (at least the 5xxx I tested years ago) is powered through the slot, not through the 6-pin or 8-pin power extenders. So Litecoin miners need powered extenders more than Bitcoin miners (at least for 5xxx and 6xxx cards, again the 7xxx series seems to draw so little from the slot, that powered extenders may not be necessary).