Great responses guys. This is the information I was seeking.
Now if only I could pull the trigger on getting a good GPU. I was never really a gamer and my computers have NVIDIA cards. Anyone want to donate a GPU?lol
Topic: What makes some GPUs better than others (Read 769 times)
scrypt asics are on the horizon, but we'll see how long it actually takes, and how much of a multiplier they run for cost vs. efficiency.
at the moment, ATI stream processors do quite well at mining, full chart of the cards can be found at https://litecoin.info/Mining_hardware_comparison.
As far as selecting a card to run, the 280x's/7970/7950's run at a nice high density and fairly good pricepoint at times; requires larger power supplies in multigpu rigs, but at the same time requires fewer processors and boards per MH/s.
this:
... was taken from https://en.bitcoin.it/wiki/Why_a_GPU_mines_faster_than_a_CPU
edit: that was for SHA256 based coins, like bitcoin, but even though scrypt is a different algorithm, the advantage for the Red Team originates from the same source.
at the moment, ATI stream processors do quite well at mining, full chart of the cards can be found at https://litecoin.info/Mining_hardware_comparison.
As far as selecting a card to run, the 280x's/7970/7950's run at a nice high density and fairly good pricepoint at times; requires larger power supplies in multigpu rigs, but at the same time requires fewer processors and boards per MH/s.
this:
Quote
Firstly, AMD designs GPUs with many simple ALUs/shaders (VLIW design) that run at a relatively low frequency clock (typically 1120-3200 ALUs at 625-900 MHz), whereas Nvidia's microarchitecture consists of fewer more complex ALUs and tries to compensate with a higher shader clock (typically 448-1024 ALUs at 1150-1544 MHz). Because of this VLIW vs. non-VLIW difference, Nvidia uses up more square millimeters of die space per ALU, hence can pack fewer of them per chip, and they hit the frequency wall sooner than AMD which prevents them from increasing the clock high enough to match or surpass AMD's performance. This translates to a raw ALU performance advantage for AMD:
AMD Radeon HD 6990: 3072 ALUs x 830 MHz = 2550 billion 32-bit instruction per second
Nvidia GTX 590: 1024 ALUs x 1214 MHz = 1243 billion 32-bit instruction per second
This approximate 2x-3x performance difference exists across the entire range of AMD and Nvidia GPUs. It is very visible in all ALU-bound GPGPU workloads such as Bitcoin, password bruteforcers, etc.
Secondly, another difference favoring Bitcoin mining on AMD GPUs instead of Nvidia's is that the mining algorithm is based on SHA-256, which makes heavy use of the 32-bit integer right rotate operation. This operation can be implemented as a single hardware instruction on AMD GPUs (BIT_ALIGN_INT), but requires three separate hardware instructions to be emulated on Nvidia GPUs (2 shifts + 1 add). This alone gives AMD another 1.7x performance advantage (~1900 instructions instead of ~3250 to execute the SHA-256 compression function).
Combined together, these 2 factors make AMD GPUs overall 3x-5x faster when mining Bitcoins.
AMD Radeon HD 6990: 3072 ALUs x 830 MHz = 2550 billion 32-bit instruction per second
Nvidia GTX 590: 1024 ALUs x 1214 MHz = 1243 billion 32-bit instruction per second
This approximate 2x-3x performance difference exists across the entire range of AMD and Nvidia GPUs. It is very visible in all ALU-bound GPGPU workloads such as Bitcoin, password bruteforcers, etc.
Secondly, another difference favoring Bitcoin mining on AMD GPUs instead of Nvidia's is that the mining algorithm is based on SHA-256, which makes heavy use of the 32-bit integer right rotate operation. This operation can be implemented as a single hardware instruction on AMD GPUs (BIT_ALIGN_INT), but requires three separate hardware instructions to be emulated on Nvidia GPUs (2 shifts + 1 add). This alone gives AMD another 1.7x performance advantage (~1900 instructions instead of ~3250 to execute the SHA-256 compression function).
Combined together, these 2 factors make AMD GPUs overall 3x-5x faster when mining Bitcoins.
... was taken from https://en.bitcoin.it/wiki/Why_a_GPU_mines_faster_than_a_CPU
edit: that was for SHA256 based coins, like bitcoin, but even though scrypt is a different algorithm, the advantage for the Red Team originates from the same source.
I don't remember the details but from what I've read, NVidia lacks a few (or is it just one?) particular integer instruction(s) required for speed of scrypt mining. While ATI can do that operation in a single cycle, coding the same on NVidia requires a few instructions, clock cycles and therefore results in hashrate loss.
That's evident not only on coin mining, but also on some password cracking software and other integer oriented tasks according to some benchmarks I've seen.
That's evident not only on coin mining, but also on some password cracking software and other integer oriented tasks according to some benchmarks I've seen.
Its my experience that the Nvidia cards are worse for mining because they are designed to have larger individual parts that are very good for rendering game graphics, but much less efficient for the less active task of creating hashes, AMD cards are better because of the many more, smaller processing parts inside of them. I'm not sure about the specialty GPU, there will most likely be more very soon.
Interesting. The design of these must pretty different in order to achieve such a disparity.
Its my experience that the Nvidia cards are worse for mining because they are designed to have larger individual parts that are very good for rendering game graphics, but much less efficient for the less active task of creating hashes, AMD cards are better because of the many more, smaller processing parts inside of them. I'm not sure about the specialty GPU, there will most likely be more very soon.
from my experience, 7950s are definately the most efficient for their money, but good luck finding them now 
r9 280x are good aswell
im not sure what makes them better tho, but i would like to know aswell
r9 280x are good aswell
im not sure what makes them better tho, but i would like to know aswell
I'm considering GPUs for LTC mining and have a question. I've noticed that some GPUs that might be comparable in the gaming arena are very different in terms of hash rates. For example, NVIDIA cards all seem to be piles of garbage for mining despite being powerful for gaming. So what causes the disparity between cards. I understand memory, clock, etc., but can't understand what features make for a good GPU for mining.
Also, I notice there are specialty manufacturers making ASICs but I'm not aware of anyone making specialty GPUs for scrypt-mining. I mean if some combination of GPU features makes for powerful hashing, why hasn't any company come up with a GPU that is designed to incorporate those combinations?
Maybe the answer is I'm a lot less educated on this than I previously thought.
Also, I notice there are specialty manufacturers making ASICs but I'm not aware of anyone making specialty GPUs for scrypt-mining. I mean if some combination of GPU features makes for powerful hashing, why hasn't any company come up with a GPU that is designed to incorporate those combinations?
Maybe the answer is I'm a lot less educated on this than I previously thought.
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