If you typically follow GPU performance as it related to gaming but have become curious about Bitcoin mining, you’ve probably noticed and been surprised by the fact that AMD GPUs are the uncontested performance leaders in the market.This is in stark contrast to the PC graphics business, where AMD’s HD 7000 series has been playing a defensive game against Nvidia’s GK104 / GeForce 600 family of products.In Bitcoin mining, the situation is almost completely reversed — the Radeon 7970 is capable of 550MHash/second, while the GTX 680 is roughly 1/5 as fast.There’s an article at the Bitcoin Wiki that attempts to explain the difference, but the original piece was written in 2010-2011 and hasn’t been updated since.It refers to Fermi and AMD’s VLIW architectures and implies that AMD’s better performance is due to having far more shader cores than the equivalent Nvidia cards.This isn’t quite accurate, and it doesn’t explain why the GTX 680 is actually slower than the GTX 580 at BTC mining, despite having far more cores.

This article is going to explain the difference, address whether or not better CUDA miners would dramatically shift the performance delta between AMD and Nvidia, and touch on whether or not Nvidia’s GPGPU performance is generally comparable to AMD’s these days.Topics not discussed here include:These are important questions, but they’re not the focus of this article.We will discuss power efficiency and Mhash/watt to an extent, because these factors have an impact on comparing the mining performance of AMD vs.Nvidia.Bitcoin mining is a specific implementation of the SHA2-256 algorithm.One of the reasons AMD cards excel at mining is because the company’s GPU’s have a number of features that enhance their integer performance.This is actually something of an oddity; GPU workloads have historically been floating-point heavy because textures are stored in half (FP16) or full (FP32) precision.The issue is made more confusing by the fact that when Nvidia started pushing CUDA, it emphasized password cracking as a major strength of its cards.

It’s true that GeForce GPUs, starting with G80, offered significantly higher cryptographic performance than CPUs — but AMD’s hardware now blows Nvidia’s out of the water.The first reason AMD cards outperform their Nvidia counterparts in BTC mining (and the current Bitcoin entry does cover this) is because the SHA-256 algorithm utilizes a 32-bit integer right rotate operation.This means that the integer value is shifted (explanation here), but the missing bits are then re-attached to the value.bitcoin kurs 12 monateIn a right rotation, bits that fall off the right are reattached at the left.bitcoin pool algorithmAMD GPUs can do this operation in a single step.bitcoin dovizPrior to the  launch of the GTX Titan, Nvidia GPUs required three steps — two shifts and an add.We say “prior to Titan,” because one of the features Nvidia introduced with Compute Capability 3.5 (only supported on the GTX Titan and the Tesla K20/K20X) is a funnel shifter.100 mh/s bitcoin

The funnel shifter can combine operations, shrinking the 3-cycle penalty Nvidia significantly.We’ll look at how much performance improves momentarily, because this isn’t GK110’s only improvement over GK104.GK110 is also capable of up to 64 32-bit integer shifts per SMX (Titan has 14 SMX’s).GK104, in contrast, could only handle 32 integer shifts per SMX, and had just eight SMX blocks.We’ve highlighted the 32-bit integer shift capability difference between CC 3.0 and CC 3.5.AMD plays things close to the chest when it comes to Graphics Core Next’s (GCN) 32-bit integer capabilities, but the company has confirmed that GCN executes INT32 code at the same rate as double-precision floating point.bitcoin bransonThis implies a theoretical peak int32 dispatch rate of 64 per clock per CU — double GK104’s base rate.bitcoin gold pendantAMD’s other advantage, however, is the sheer number of Compute Units (CUs) that make up one GPU.

The Titan, as we’ve said, has 14 SMX’s, compared to the HD 7970’s 32 CU’s.Compute Unit / SMX’s may be far more important than the total number of cores in these contexts.Next page: Wrath of the Titan…Bitcoin Sign up or log in to customize your list._ Here's how it works: Anybody can ask a question Anybody can answer The best answers are voted up and rise to the top up vote down vote favorite 2 I have been searching Google all day and cannot find any real information.I'm looking for information in detail, such as specifications or the qualities of the GPUs that make the differences.mining-hardware gpu-mining up vote down vote Summary: different approach to calculations.Nvidia GPUs are more like CPUs, in that they have only a few processors that do work, but faster.ATI GPUs have slower processors, but a lot more of them.You can find a more complete description on the relevant wiki page : 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).