UPDATE: Steps I did to do the same is on the bottom of this post.
UPDATE2: Tried 8 GPU, and it was blank screen/no post or boot, so 7 GPU is max with this setup.Well, after reading all this talk about motherboards with 7 PCIe slots for 7 GPU rigs, it got me into the hype of wanting it too. But all my rigs are Asrock H81 Pro BTC motherboards and didn't want to buy a new motherboard for each of them, just to add a 7th GPU. I've read about PCIe switches/hubs and decided to give it a try and want to share my findings with others.
Here's my setup:
Motherboard: Asrock H81 Pro BTC
Processor: Intel Pentium G3240
Ram: 8GB G.SKILL Ripjaws Series
Storage: 60GB SSD
Power Supply: EVGA 1300 G2
Cards: (7) XFX 480 8GB Reference (Custom public bios, thanks @Eliovp)
PCIe Switch/Hub:
https://www.amazon.com/PCI-E-Switch-Multiplier-Expander-Expansion/dp/B01ERXUEOMCustom power cables for the EVGA to power 7 GPU and 7 Risers (thanks @sidehack for the nice quality cables, and a custom CPU to VGA modular cable
https://bitcointalksearch.org/topic/fs-gs-server-psus-boards-kits-stickminers-gpu-riser-power-made-in-usa-940317)
Drivers: 16.11.5
Tools:
http://www.overclock.net/t/1609782/watttool-a-simple-tool-that-combines-overclocking-with-vrm-monitoring-tweaking-for-rx-400-seriesO/S: Windows 7 X64 with 6+ GPU MOD (
https://lbr.id.lv/6xgpu_mod/)
Bios settings changes: Set PCIE2 Link Speed to gen1, and disable onboard GPU, Also, see post #44 for all my bios settings here
https://bitcointalksearch.org/topic/m.18803505NOTE: HDMI Dummy plug used because sometimes it would not boot without a display connected so I used a dummy plug 24/7 since I manage it remotely with teamviewer
https://www.amazon.com/CompuLab-fit-Headless-Display-Emulator/dp/B00FLZXGJ6/And a shout out to @Spotswood for the nice quality open frame (
http://spotswoodcomputercases.com/wp/?page_id=8791), puts my PVC frame to shame:
And a look at the PCIe Switch/Hub nicely mounted:
Now time for the good stuff...
I downclock/lowered my numbers a bit instead of going for the 31+ Mh because power consumption and heat is a big factor for me.
Here is my Claymore mining ETH at a stable ~204 Mh:
Here is my GPU-Z:
Here is my WattTool settings (results may vary):
Now after all that is done, here is my Kill-A-Watt meter:
So 204 Mh at about 976 watts is pretty dang good for me. Just a shy under 1000 watts for a 7 GPU rig setup with 200+ Mh.
Now one is done, time to do the others (fun stuff)!
Here are my steps:
1. Install the hardware of the PCIe splitter (only need power from molex or sata, not both) and GPU's and connect everything.
2. Boot into BIOS and change PCIE link speed to gen1.
3. Boot computer in safe mode.
4. Run DDU to install all old drivers from here
http://www.guru3d.com/files-details/display-driver-uninstaller-download.html5. Reboot computer normally.
6. It should show 7 gpu in device manager, if so, install drivers 16.9.1 (I have tested and it seems the most stable for me)
http://support.amd.com/en-us/download/desktop/previous/detail?os=Windows%207%20-%2064&rev=16.9.17. Once driver's are installed, do not reboot computer. Download this and run it and modify registry
https://lbr.id.lv/6xgpu_mod/8. Now reboot, and everything should work.