Bitcoin Forum

Hello

I have Asus P5K motherboard which I bought 3 years ago:
http://www.asus.com/Motherboards/Intel_Socket_775/P5K/#specifications

http://www.asus.com/websites/global/products/yS3ZeqfUdCTCIFT2/P_500.jpg

The slots are:
2 x PCIe x16 (blue @ x16 mode, black @ x4 or x1 mode) supports CrossFire Technology
1 x PCIe x1
3 x PCI

I want to choose video cards for mining. Here are my questions:
1. Please advise which videocards I can use here. Are all modern videocards like recent Radeons 5XXX/6XXX supported by this motherboard?
2. I see there are 3 different PCIe slots, can I use all of them at a maximum GPU speed?
3. Which video card meets the best performance/price ratio?
4. Should I set up cross-fire between the cards or it does not make sense for mining?
5. I see that the same video card from different vendors has too different prices. For example, Radeon 5850 from XFX ATI costs $585 whereas from Sapphire costs just $160 (http://www.amazon.com/s/ref=nb_sb_ss_i_4_12?url=search-alias%3Daps&field-keywords=radeon+5850). Is there any difference in mining speed between vendors? Should I pay more or not?

I will be mining under Gentoo Linux.

thanks

That sapphire 5850 is permanently out of stock, like most of the other 5800 series.

1 yes, 4 no

I got this mobo and use 2x 5870 cards.
There are only 2 PCI-e slots on this board as far as I can tell so you can only use 2 cards.

Or 3 cards with an extender.

I got an extender for the PCI-e 1x slot (to PCI-e 16x) but when I connect a 5870 it does not show up on the device list (linux: AMDOverdriveCtrl -h command lists only 2 cards).

Do I need to enable this PCI-e 1x slot in the BIOS? Any advice welcome.

Have you checked if the extender is working correctly? Have you tried to unplug one of the cards in the 2 primary slots, and see if the extender works? Are you sure the PSU is big enough? Just trying to help. I have the same mobo, but haven't tried a 3rd gfx yet, getting one soon but still need an extender cable, so can't confirm or deny anytime soon. I haven't been able to find anything online about the 1x slot not working when using the 2 other ones tho.

Does anyone know for sure?

1) Any video pci-e compliant video card. Even the pcie 16x rev 2.0.
2) You can use them all at full speed for mining. I wouldn't suggest gaming with all 3.
3) 5770 is the best $/mhs. But go with the 58xx or 6950's (with or without bios mod to possibly unlock extra shaders). I keep picking up used 5870's for $200, and that is a $2 per mh/s. That's what you should shoot for, 2 to 1. Don't get 6850's. For the extra 30, pick up at 6950, it achieves nearly same performance as the pricier 5870.
4)Do not set up cross fire. Use dummy plugs, I see you are running linux, you might not have to use dummy plugs.
5) Same cards from different vendors WILL NOT matter. What will matter is if the card comes with a factory overclock and what style cooler. Try to pick up the reference centrifugal coolers, these exhaust the air out the back of the case, and makes it much better for keeping the heat from recycling in the case.

Anything else, PM me.

NOTE: You do not have to use an extender if you chop the back off of the Pci-e 1x slot. Obviously, this voids your warranty. but the board you purchased was probably about $30 bucks.

I have the same problem, use an extender to connect the second/third 5870 to the pci-e x1 slot and it does not get recognized, even lspci did not show the adapter infomation. Any one have a similar board?

In my opinion, if the second pci-e x16 slot is operating at x4 mode, it will disable the pci-e x1 slot, but in BIOS there is only one option to force the x1 mode for the first pci-e x16 slot, not the second

I am using the board with 3 gfx's, the pci-e x1 slot can be used just fine, but you need to short pin A1 with B17 ( https://bitcointalk.org/index.php?topic=36061.0 ), I used a cable tie (got loads of them whenever I get hardware with cables), with exposed ends, it's been running just fine for 2-3 weeks now.

Thanks, shorting these 2 pins really did the trick!

I tried this too some weeks ago, exactly the same method (a cable tie with exposed ends) but no workie for me.
It does not seem to matter if I short A1 and B17, it boots exactly the same (Linux). I tried the PCI-e 1x to 16x extender on another motherboard and it works there, so that is working. (I even bought 2 of those extenders just in case).

I will try to do some BIOS settings.

(Yes, the PSU is powerful enough to feed those 3 x 5870 cards).