I have tried a few different miners and a couple different pools but it is not working.

I have a Radeon HD 6950 card (with the extra shaders unlocked using this method, with +20% power on)
When I start the miner it shows me my MHash/s but it is getting hardware errors and no shares are being accepted and none of them are being rejected, it is just hardware errors.

I used to mine and it was working fine (though this was a couple years ago now, but I was using the same GPU)

I have tried using GUIMiner, PheonixMiner and DiabloMiner.

I've gotten a few different errors,
"No JSON object could be decoded"
"Verification failed, check hardware! (0:0:Cayman, 38570c89)"
"IO errors - 1, tolerance 2"

I've had a look around but nothing really seemed to help.

From what I've seen the 5830 looks good and is one of the highest mhash per dollar

have a look at this

Although the 5870 can generate more and has a higher mhash per watt

So on the hardware comparison page it says that the 5870 can get between 313 and 438 mhash now on a quick check on google shopping I've seen that theres a few with large price differences. Some are £140 and others are £300.

Now I am considering getting one sometime in the (hopefully) not too distant future, but my question is how much difference is there between the different ones? As some have the same memory and I think they all have the same number of cores etc. (Mean the one with the same memory)

Also how will the differences change the mhash?

EDIT: It actually turns out that they are in fact all the same card.... which is weird, but whatever

I just found this

"SDK 2.1 not supported on 69xx. "

So nevermind then, thanks for your help though

I feel silly for asking this but whatever.
I am unsure as to what version I have but it is most likely the most latest one, but how can I change the version to 2.1 in order to improve upon my mhash etc?

I am using windows 7 64-bit and a 6950 (not unlocked to a 6970 yet as I need a better case first).

Alright then, I shall when I get some, becuase you really have been a help 

Oh thanks very much it worked, now I can do more whilst mining

I am also having this problem, I have an xfx 6950 and the pc crashes as soon as I start watching a flash video.

I normally manually turn off the mining but sometimes I forget to and it crashes or sometimes I forget to turn it back on.

How do you disable harware acceleration for videos?

Yeah I am also getting a load of "warning: job finished, miner is idle" but i'll just continue mining

I have this motherboard and the xfx 6950, i am thinking about getting another one.

So I'd get one of the x1 to x16, but would I need the molex connection?
And how would I put the gpu in the case as the cable would cause a gap between the x1 and the card wouldn't it?
Also how would I use that open ended x1 slot? would that mean that you'd have to take off the one you have and put that in its place?

So in that case I can just use the one I have atm, well thank you you've been a great help.
But what is this about dummy plugs, if you are running windows does gpus not in crossfire need a dummy plug in to emulate a screen attached or something?
Just to make sure

"Great for intense gaming & Bitcoin mining" is what it says on the site for the extender, what effect would that have for none mining purposes?

I've been looking for a motherboard that would let me have two gpu's for mining (6950's) although it will have to be decent as it is a pc that I use for gaming.

So my question is, does the fact that 1 slot may be x16 but running at x8 make that much of a difference (if any) as the only motherboards that don't are £150 plus ($250)

Here's a couple that I've came across, tell me what you think

http://www.ebuyer.com/product/193443
http://www.ebuyer.com/product/255175

Also if those are no good, or you think there may be ones that are cheaper that may be usefull could you please post a link?

Oh thanks I managed to find the door hanger and it is the "695A-CNFC" so a reference one, thanks for your help.

Is there a motherboard you'd recommend that isn't too pricy and would let me have two graphics cards?

As in the sleeve or the box itself?

EDIT: I checked the box and it doesn't and it turns out that I lost the sleeve

I've had a look at shops searching for that product code and they all have the picture that looks like mine, so it probably is.

It says it has normal display ports, but the picture (which looks like mine) has mini display ports (like mine does)

This is the model you speak of

Well I only have 1 pcie x 16, 2 pcie x1 and 1 pci so I would need to get a new motherboard, have you got any ideas for decent ones that aren't too pricey?

Also is my gpu a reference card?

And thanks for your help so far

Thanks very much I think I'll be considering a new cpu, are there ways of using multiple graphics cards without spending 100-200 quid minimum on a motherboard?

Also if I did buy another gpu, would I need another psu? (As I don't have enough money to essentially replace most of my pc)

Before I list my parts I just want to clarify that I don't have much money and am in college so I can't fork over a large amount of money.

This is a gaming/mining rig and won't be mining all the time.

I have:
This motherboard
This CPU
8 GB of this
This Power Supply
And This Graphics Card
I have a crappy gigabyte case atm but am about to get a antec dark fleet DF-85

I get roughly 300mhash/s

What can you suggest for me to get more mhash?

Yeah I got it, sorry for taking so long to respond, its just that I was tired, due to the fact it was nearly 4am here.