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Title: Importance of GPU RAM for Litecoin Mining Post by: W-M on April 02, 2013, 10:02:59 PM Hello there, everyone,
I have lately been looking into mining. I am new, and right now am deciding if/what hardware I want to buy. Mining Litecoin seems very lucrative at the moment(in comparison with BTC at least) because of the current difficulty and of course the near future when many people will use their ASICs on the Bitcoin network. On the internet I've seen some interesting GPUs for sale, and of course each model has a different average hashing rate. However, some models also have variations with a different amount of RAM installed, e.g. both a 1GB version and a 2GB version. This brings me to my question: Does the difference in on-board RAM change the Litecoin(Scrypt) hashing rate of a card much? Thank you, ~W-M Title: Re: Importance of GPU RAM for Litecoin Mining Post by: W-M on April 03, 2013, 11:12:37 PM I haven't found an answer yet. Is there anyone out here?
Title: Re: Importance of GPU RAM for Litecoin Mining Post by: CoinHoarder on April 03, 2013, 11:16:08 PM I wouldn't think that the increased RAM would cause any difference in hashing speed.
I think the bottleneck is the memory speed / engine speed. Title: Re: Importance of GPU RAM for Litecoin Mining Post by: AmDD on April 03, 2013, 11:24:13 PM I dont mean to thread-jack but I have a similar question...
Does litecoin mining use more system ram or GPU ram? I know scrypt is very memory intensive but which memory does it use? Title: Re: Importance of GPU RAM for Litecoin Mining Post by: CoinHoarder on April 03, 2013, 11:29:02 PM I dont mean to thread-jack but I have a similar question... Does litecoin mining use more system ram or GPU ram? I know scrypt is very memory intensive but which memory does it use? The way I understand it, it uses both, however 2 Gb RAM on the mobo is all I've ever needed for any rig I've built (LTC or BTC.) Title: Re: Importance of GPU RAM for Litecoin Mining Post by: CoinHoarder on April 04, 2013, 12:24:24 AM Also... I meant to add that because a rig with 8 GPU cores (8Gb total Video memory) hashes at the same speed with 2Gb system RAM or 8Gb system RAM, that it uses the video card's memory mostly.
Title: Re: Importance of GPU RAM for Litecoin Mining Post by: Vorksholk on April 04, 2013, 12:27:54 AM You may get better results if you post in Alternate Currencies :)
Either way, from what I understand a higher memory clock is much more important than the actual amount of RAM on the card--1GB should be plenty. If you are talking about a 7xxx series above a 77xx then you want to be looking at getting a 0.57-0.6 ratio between core/memory. Title: Re: Importance of GPU RAM for Litecoin Mining Post by: philips on April 04, 2013, 02:01:56 AM I dont mean to thread-jack but I have a similar question... Does litecoin mining use more system ram or GPU ram? I know scrypt is very memory intensive but which memory does it use? Depends on the software used to mine. Reaper use the system RAM for mining, while cgminer is using GPU RAM. Ex: 4 x 7970 are OK with 2GB RAM if using cgminer, but for reaper you will need around 8GB. Title: Re: Importance of GPU RAM for Litecoin Mining Post by: anonadeus on April 09, 2013, 11:27:51 PM Still not sure if this question has been answered. Can a 6GB card outperform a 3GB card if core, mem and voltage are identical? If so, by how much?
Title: Re: Importance of GPU RAM for Litecoin Mining Post by: middlemarkal on April 09, 2013, 11:53:22 PM Still not sure if this question has been answered. Can a 6GB card outperform a 3GB card if core, mem and voltage are identical? If so, by how much? a 7990 with 6 gig is double the speed of a 7970 with 3 GIG (also 1 GPU instead of 2 ;D) bad exemple. 2 gig 7870 or 1 gig 7870 is a better question, don't know the answer Title: Re: Importance of GPU RAM for Litecoin Mining Post by: matauc12 on April 09, 2013, 11:57:50 PM RAM isnt used to full capacity on 7xxx models. What is important however is bus speed. Which is the reason (most likely) why the Tahiti LE doesn't compete with Tahiti shader for shader.
Title: Re: Importance of GPU RAM for Litecoin Mining Post by: dreamwatcher on April 10, 2013, 12:52:00 AM From the Scrypt site http://hackage.haskell.org/packages/archive/scrypt/0.3.2/doc/html/Crypto-Scrypt.html (http://hackage.haskell.org/packages/archive/scrypt/0.3.2/doc/html/Crypto-Scrypt.html) Quote Parameters to the scrypt function Scrypt takes three tuning parameters: N, r and p. They affect running time and memory usage: Memory usage is approximately 128*r*N bytes. Note that the scryptParams function takes log_2(N) as a parameter. As an example, the defaultParams log_2(N) = 14, r = 8 and p = 1 lead to scrypt using 128 * 8 * 2^14 = 16M bytes of memory. Running time is proportional to all of N, r and p. Since it's influence on memory usage is small, p can be used to independently tune the running time. From: http://cryptocur.com/litecoin/ (http://cryptocur.com/litecoin/) Quote With the scrypt parameters used in litecoin’s implementation (N = 1024; p = 1; r = 1), each thread needs about 64-128 KB depending on the lookup_gap and thread_concurrency settings when mining with a GPU. This makes litecoin actually ideal to mine with a GPU, GPUs have very fast memory (bandwidths going into hundreds of GB/s) and generally 128-512 KB RAM per stream processor. Title: Re: Importance of GPU RAM for Litecoin Mining Post by: anonadeus on April 10, 2013, 01:36:08 AM Ok, here is a concrete example/problem.
3 Sapphire 7970s: $410 http://www.superbiiz.com/detail.php?name=AT-H7970CB Mfr Part Number: 11197-03-40G Engine Clock: 950 MHz Boost Clock: 1000 MHz Video Memory: 3GB GDDR5 Memory Clock: 5700 / 5800(Boost) MHz Effective Max Resolution: 4096 x 2160 Connectors: DVI-I, DVI-D, HDMI, DisplayPort Dimensions (WxLxH): 120.0 x 280.0 x 40.0 mm $436 http://www.superbiiz.com/detail.php?name=AT-7970GHZ Mfr Part Number: 11197-12-40G Engine Clock: 1000 MHz Boost Clock: 1050 MHz Video Memory: 3GB GDDR5 Memory Clock: 6000 MHz Effective Max Resolution: 2560 x 1600 Connectors: DVI-I, DVI-D, HDMI, DisplayPort Dimensions (WxLxH): 135.0 x 285.0 x 45.0 mm $584 http://www.superbiiz.com/detail.php?name=AT-7970_6G Mfr Part Number: 11197-05-40G Engine Clock: 1000 MHz Boost Clock: 1050 MHz Video Memory: 6GB GDDR5 Memory Clock: 6000 MHz Effective Max Resolution: 4096 x 2160 Connectors: DVI-I, DVI-D, HDMI, 2x Mini DisplayPort Dimensions (WxLxH): 115.0 x 275.0 x 52.0 mm I'm assuming the $410 one is the best choice, anyone one else have thoughts on the matter? |