Bitcoin Forum

I'm looking to purchase an ATI Radeon 6950 card, either 1GB or 2GB GDDR5 RAM. Is it worth spending the the extra money.

Are there any benefits on the Hash rate with the extra 1GB of Ram?

Thank you.

But, how much of a % in gained in the hash rates? 

Example in prices :

1GB @ $250 CAD VS 2GB @ $300 CAD

I'm looking to buy 5 cards. Is paying 20% extra worth it?  $1250 vs. $1500

Than you.

Shut up jCole, no trolling! >:( Your post has been reported.
The additional RAM is of no significance at all for mining, damn it!
In fact, more memory means higher energy use and temperatures.
Your mining speed will ultimately only be affected by how far you feel comfortable overclocking the card.

I was under the impression that underclocking memory is benificial as it lowers temperatures,So the difference between 1GB or 2GB would make little difference

non sequitur
Its not because memory speed makes no difference that capacity wouldnt either. As it happens, this is indeed the case, bitcoin mining requires something like 100Mb vram, anything more is pointless, but you couldnt conclude that from the fact everyone underclocks

Use the past tense when necessary Holliday. The operative word is could.
The same gpu core chips are being used for both 6950 versions and the 1GB version used to be just as unlockable (http://www.legitreviews.com/article/1608/1/).
Since your article (http://www.techpowerup.com/articles/overclocking/159) was published, AMD decided to laser-cut the inactive shaders in the 6950 chips instead of disabling them in the bios (the transition was made in 2011Q2 IIRC).
On a similar note, all new AMD CPUs that may have had unlockable cores are getting the same "special treatment".
Any 6950 may be unlockable if it's using the old core revision from before the change but those chips are extremely scarce now.

I'd like to make this fact painfully clear: AMD uses the same chips for 6970 and 6950 cards, only with some shaders disabled in the case of the weaker model. Those shaders could be re-enabled by flashing the bios. Unfortunately for the users, the internal policies at AMD were changed and now the shaders on chips sold as 6950 are being laser-cut. There's no going around that.

Hey, Holliday, I removed some sting from my previous post.

Apparently, unlockable CPUs and GPUs were hitting AMD's revenue to a greater extent than expected.
A bloody shame what AMD have done but they have been haunted by constant financial issues (which are the main reason AMD sold out all their fabs) and need every penny of that revenue badly :-\

BTW, the 6950 chips aren't all perfectly good - any chip with shader defects is down-graded to 6950 status if at least 1408 shaders are in fine working order.

Make sure you have the necessary RAM as well.

2GB GFX card and 4GB ram won't work well.

From what I found while googling, the old 6950 1gbs might be unlockable (luck is still a big factor in getting one that is unlockable, but it is possible).

Aside from that, reading the mining hardware comparison chart, it does not look like 2GB 6950s are any faster than the 1GB ones, so I'll also say just get the 1gb ones. (You could also search for some old 6950s and try unlocking them if you are feeling lucky)

*Some* 6950 1GBs ARE unlockable, read the reviews and Ctrl-F search for unlock: http://www.newegg.com/Product/Product.aspx?Item=N82E16814125385
Stay away form XFX, none of them appear to be unlockable 1GB including some 2GB.

Some 6950 are unlockable PERIOD.
The amount of system memory has nothing to do with unlockability.
Unlockability depends solely on the GPU chip.
100% 6950 chips used to be unlockable early on but not all of those were defect-free.
In 2011 AMD changed the rules, however, and newer chips are having their shaders laser cut at the factory specifically so that they can not be unlocked.
It's a total crapshoot and the only thing you can count on is that the newer revisions won't unlock.

If you have any choice, aim for the card revisions from 2011Q1-2011Q2. Those are more likely to unlock.

I have a XFX 6950 2GB and did the shader unlock a long time ago to make it a 6970. I have been running this card for many months and it is very stable unlocked and overclocked 950mhz, temps never above 65c (open frame rig, large house fan). Keep in mind only the old cards are capable of the unlock.  With cgminer 2.1.2 I can get 415 m/hash out of this card which I am very pleased with.

6950's 1GB are going for about 200min currently. If I had to decide on a new card I would pick a new card using this priority....

1. 5970 - picked up 4 of them for 354 each. Harder to find now though at decent price.
2. 5850/5870 If you look around for a while these can be found at a decent price, keep an eye on the Goods Marketplace here. In many cases you can get one of these for 150 or less. When overclocked it may get 6950 hashrate.
3. 6950 - one advantage of that route is the resale value will be higher.

A lot to consider on getting the right card. Memory size don't sound like it, more on the unlock-ability of shader. Some new cards don't have this option.

Does it matter on the sticker manufacture of this card. To name a few manufactures like Gigabyte, Sapphire, XFX Powercolor and HIS.

Most of the feed backs on Newegg.ca are the gamer side of things, not the bitcoin user.  :(

Which manufacture do you think shows you the power for the buck!! Show me the Power!!!

I know "Everyone" have research to made this decision on what they run in their mining system/rack.  From what you read to what you have experienced are sometimes totally different.

What have you picked and why?

Thank you

I went with the XFX brand because of the reviews I read on newegg. When I got the card it seemed like a well manufactured quality product.....I still stand by that statement. They warranty is probably better than other vendors as well. I can't recall the specifics of it but remember it being better than others. When I bought this card I bought it for gaming before I knew of bitcoin, I'm glad it easily found a home here.  And even happier I didn't settle on an Nvidia card at the time!

Just want to toss my recent experience in.

i bought an off the shelf 6950 at frys electronics last week.. and it was still unlockable..

2gb you get the 6970, worth it to me.

I guess it does make sense to get a 6950 then hacked it to a 6970..

Thanks all

You can see the differences here http://en.bitcoin.it/wiki/Mining_hardware_comparison

6950 vs 6970 is worth ~30MH/s.
1GB vs 2GB is worthless for mining (but useful for gaming at 1920+ with high/ultra details)

You will typically underclock your memory to ~1/3 of your card's gpu clock, when using a phatk kernel with vectors 2 and worksize 256.

Good point.

Going by the same chart, the price difference given is $100 for the same power.

if you plan on flashing the 6950 over to the 6970, then you need to make sure you order a reference card. If you do not then you will not be able to flash it, also you might want to consider using the firmware with the unlocked shaders, not the 6970 bios as it has voltage increases that could cause damage.

Also a 2gb 6950 will not perform any better then a 1gb one, unless you are using a resolution over 1920x1200 or so.

Don't count on that

I have some 6950 Asus DCII 1G, non-reference cards. 02 cards are unlockable, others are not.

It is up to your luck  ;D

6970 is just too expensive compared with 6950.

But I think 7950 is the way to go in the long run :)

Save your money. I have 6950 running @ 930 = 385mhash. More memory is useless for mining