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I read someone on this forum that with the 12.8 driver, dummy plugs are no longer needed. Just got two windows machines up and running using the 12.8 driver, but I can't seem to access the extra videocards on the motherboards.

I didn't know if the rumor was false, and that I'd have to go make myself some. Or if it is true, and something else is causing the issue that dummy plugs won't fix.

It's very odd, at one point of time, when I was bitcoin mining, I didn't need dummy plugs, then for some reason, all of a sudden I needed dummy plugs. Can't hurt to try. Only few bucks for the resisters at radio shack. I'm sure you already have the adapters.

I haven't needed the dummy plugs since before 12.6 on win7 boxes.  Are you sure you have done a clean install?

I built 3 rigs recently on Windows 7 and the only dummy plug i installed was on the 1st card (I run them without any connections except power/network and use VNC to remote).  All cards after the 1st in each rig did not need a plug.  This is using 13.1 ATI drivers and Win7 64-bit.  Hope that helps.

Yeah, I just did a clean install on both rigs yesterday. It seems that the cards are detected by windows, except for the first card. And that's with running the cards in both the 1x and the 16x slots. I guess I'll be stopping by radioshack later today.

Mine would run without dummy plugs but Afterburner would not detect and let me select it without one.
Window 7 64 and the latest beta drivers for the cards.

Interesting, let us know how you get on mufa.

It seems that every pc shop and radioshack within 50 miles of me is out of stock. One store did have 78 ohm resistors at 1/8th watt. Does the wattage matter? Would say a ~48 ohm 1/4w or 1/2w work? I'm trying to figure this out.

Thanks

Oh, I forgot. One of the radioshacks had some 100 ohm resistors. Would that work?

I really don't know much about this kinda stuff, and don't want to fry my cards lol

Yes

Yup, 75-78-100 ohm.

I walked in there and was like "Hey, I called earlier about those resistors. Where are they?" "Right over here, sir. How many do you need?" "I... I think I'll just take all of them..." So I bought out all 100ohm and 150ohm from radioshack. Was kinda funny. :) Although I feel bad for any local miners looking for some in my area. Those were the only resistors being sold by a store within 30 miles. But yeah, talked to a friend of mine and he said you can run two 150ohm resistors in parallel to make a 75ohm one. I need a bunch, so I bought everything. Going to go give them a try, and will report back in a little while.

Alright, having issues. I made one, and it didn't work. Made another with the resistors going the other way, but that doesn't work either. https://i.imgur.com/UUeymH6.jpg

What am I missing? I can't get windows to detect my other cards. :(

Update: Plugged all three cards into the machine and gave each of the extra cards the opposing dummy plug. Windows got to the desktop, then started going haywire. Unplugged both dummies, but it wouldn't stop. Rebooted without the plugs, and windows now recognizes all three cards. Not sure what I did...

Here's the instructions I used

http://www.overclock.net/t/384733/the-30-second-dummy-plug

That's kind of normal with Windoze, just keep rebooting till it works :) Maybe it will keep working?

+1 that is the instructions I have used as well. Worked a treat back then.  Maybe the 100ohm is not enough resistance on the rgb channel. Try doubling up 2 100s and see if it clears up.

How do I do this? I heard that if you run them one way, it'll be 200ohms. And if you run it the other way, it will be 50ohms. How do I know which way I should have them flipped? They do have different colored lines, but I don't know what they mean.

I don't think you need dummy plugs.. You're doing something wrong..  12.6+ you should be good without them.

As of right now, everything seems to be working fine without dummy plugs. Although I haven't tested the next rig yet.

Connecting two resistors of the same value in parallel halves the resistance.  Connecting two resistors of the same value in series doubles the resistance.

I'm using 68 Ohm resistors so two 100 Ohm in parallel will give you 50 Ohms or two 150 Ohm in parallel will give you 75 Ohm.

I use Catalyst 12.1 and yes if I don't use dummy plugs mining will work, usually.  But strange things happen.  If I use a dummy plug on my 2nd GPU and extend the desktop to it it always stabilizes.  Maybe that is just my system, I don't know.  But I have had the same results with multiple catalyst versions with WinXP and Win7.  So I just use the plug.
Sam

If you are not needing the dummy plugs then that is great. You really shouldn't need them anyway.

As to doubling up the resistors, keep the lines going in the same direction, connect with a drop of soldier (or twist them), then you can use a multimeter to find the correct orientation for the resistance you want.

no dummy plugs needed since the 11.x drivers.

Alright, having issues on that other rig. So far, I've tried using a 100ohm dummy, a 75ohm dummy, and an actual second monitor hooked up to the 2nd card. Nothing seems to get it to work. I figured it might just be the card, so I swapped it out with another one that works, and I'm stilling having issues. I think I've narrowed it down to either the Motherboard/BIOS setting or some sort of software setting in Windows. Tried reinstalling the 12.8 driver, thinking I might need to have all the cards attached when I install the driver, but that didn't work either. Is there some sort of setting for the PCIe slots that I am suppose to configure? COM port, I/O something jibber jabber? It's an MSi K9N Neo-F V3 board. Has one PCIe x16 as the primary, then two PCIe x1 slots.

One question, does that board require shorting the pins of the x1 slots to see the cards?

Good idea! Which two pins was it? Gonna start looking for that thread right now...

EDIT: Found it. Gonna try it real quick a report back https://bitcointalk.org/index.php?topic=36061.0

Its pins A1-> B17 I believe. Its been a long time so don't quote me yet. ;)

EDIT: here you go: https://photos-6.dropbox.com/t/0/AAD6MxYwwvztgFUKt20XOsc_HXSGu9m6Pisq0LAL52DNyg/12/76249230/jpeg/1024x768/3/1367632800/0/2/2013-04-06%2017.48.11.jpg/pgSDOBbjfORRd1cA35KZ0JQqVzTGTe_5ni4_jpD6SBo

 ;D WOOHOO! That worked! Lol, but video will only come out of the 1x slot now.

Thanks Cablez, you saved me many hours of troubleshooting. Got a BTC address? I want to tip you, but you don't have one in your sig.

i'm not sure if i missed it or no one mentioned it, but resistors are not directional. there is no right direction, just parallel vs serial rules stated earlier. diodes are directional, but you are not using them.

Yup, I first wondered that myself. I called up a good friend of mine and asked him if it mattered, and he told me it doesn't. I used one of those electric meters with the probes to further make sure I was making myself a 75ohm resistor instead of a 300ohm resistor out of those 150 ohm resistors.

I am glad that worked out for you. It was a puzzler. ;D

No need for a tip, just helping my mining brothers and sisters when I can.

Thanks dude! Then remind me to buy you a beer some day when we're all rich and famous. :)

Will do.  :D