Q about k/h hash rate on higher end cards..
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So last night I upgraded one of my systems. My buddy who supplies my hardware made an interesting observation. He said, if you are running a lower end CPU processor that does not support the full PCI-Express 3.0 slot, does that keep the GPU from utilizing the full speed of that bus, thus keeping your hash rate from it’s potential? I thought that it made sense, so he is going to bring me an i7 a little later. In the mean time I was wondering if someone could put in their 2 cents in, and maybe confirm or deny this observation… All insight is appreciated:)
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I don’t think it makes a difference, people do run and mine GPUs from PCIe x1. The lanespeed of PCIex1 is still suffice for mining.
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Thanks ShadowEW, that’s a good point. Although, on PCIe x1 wouldn’t it still give maximum bus speed to the GPU because it is fully supported by the CPU? It just seems like there would be a processing limitation without full support. I know I could be way off on this, but it’s always nice to get an outside perspective. I guess after I get the i7 I will know for sure… Thanks again for the insight:)
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The amount of data transferred to the card and back is miniscule and blazing fast even if it was PCIE version 1.0 and a X1 slot. The time you wait is the time the card needs to crunch the numbers. Faster CPU does nothing. I run 2 7950s on a core i3 each capable of pumping out 650+ Kh/s at 72 degree celcius. That’s pretty much in the upper range you can get with those.
Tuning the settings of your cgminer and then providing adequate cooling, those are what really make a difference.
A faster CPU could lend you a couple more kh/s if you run a miner on it as well.
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Thanks ChristianRiesen, I have a feeling you and ShadowEW are right. Although, my friend still wants to see what the i7 will do. I won’t complain though, because I’m getting an i7 out of it;)
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Try it and report your findings back please. Many people don’t believe it when one person alone says it :)
You can run the cpu minerd with the i7 and it will do great.
Oh and as a side note, I ran on another machine cgminer and minerd for 4 days straight, the cpu was used in total for about 2 minutes from cgminer. So yeah, not much happening there :)
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If processor comes with a decent integrated video like AMD A8 or A10 do, then it makes some difference. Intel HD4000 video is a junk not worth any use.
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My friend said he will try to come by tonight to swap it out, but I will let you all know how it goes…
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Okay, for those of you that were curious. The i7 did nothing to increase the performance…
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[quote name=“J4c0b5L4tt3r” post=“4423” timestamp=“1368982231”]
Okay, for those of you that were curious. The i7 did nothing to increase the performance…
[/quote]Haha ok, at least you know now :)
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About the only thing I heard that will increase performance is more ram, enough to match your cards.
(I dont know if thats rubbish or not)
In my case my rig has 16gb of ram for its 12gb of ram in the cards, I really dont know if this makes a difference but I’m getting great figures from my cards, just under 670Khash each(with overclocking). I think I might even be able to get over 700khash, if I play my cards right. (no pun intended ::) ) -
Hi pyxis. Well, I have 16g myself. It was more of my friend speculating about the processor. Just out of curiosity, I’ve always thought overclocking takes away from the longevity of the cards, am I mistaken?
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[quote name=“J4c0b5L4tt3r” post=“4623” timestamp=“1369089761”]
Hi pyxis. Well, I have 16g myself. It was more of my friend speculating about the processor. Just out of curiosity, I’ve always thought overclocking takes away from the longevity of the cards, am I mistaken?
[/quote]No your not, it does cut down the life, but the way I see it, you make more now rather than later with coins. My main worry now is summer, if its gets too hot i will have to reset the cards back to 615Khash at normal settings.
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As you have discovered, the CPU does nothing to aid in the the performance of GPU miners.
Also, the amount of RAM makes no difference to the latest versions of CGMiner either. I have 4x 7970’s hashing at ~755KHs each on rigs with 4Gb RAM but CGMiner only uses ~150MB. I still have 2.6GB Available (1.2GB free).
Overclocking the cards doesn’t noticably affect the longevity of cards - Over volting and/or heat does. Keep 'em cool at stock voltages and you’ll be fine.
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@pyxis Yeah, I’ve already had a casualty from the heat. I’m glad it’s still under warranty… Although, it may be a few days before I’m full steam again… I just shoot for the highest hash rate with zero h/w errors… I’ve been pretty lucky so far… Well I hope it stays cool for you:)
@Nutnut I’ve kept all mine stock, but I have been having issues with the heat, which I’ve been trying to remedy… So far I think I may have it worked out, but only time will tell…
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Let’s be clear about this: The amount of ram required is trivial. More ram won’t help. The amount of hashing a CPU can do is minuscule compared to a GPU. A i7 quad xeon should get about 24 Mh/s, a 5770 running on an i3 will get 250 Mh/s when tuned correctly. The bang for your buck is easily in favor of GPUs.
Number one factor is CPU/GPU speed. That’s basically ALL that matters. When running scrypt, you MAY get a few extra Kh/s by overclocking your GPU ram if your running more than 600 Kh/s, but even then the limiting factor is going to be your GPU clock speed by far and away. When doing it on your CPU, you’re never going to max our your ram, nor your bus. Ever. The CPU will be pegged, and your DMA controller will be practically idle.
You see those little USB BlockEruptors? I bet then don’t have more than a few megabytes of ram on them. Notice I said megabytes, not gigabytes. Yet they outperform a 5770 with gigs of ram. It’s ALL in the Ops/second, not the storage size.
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When i first build a rig with 1x 5850 i got 512MB ram installed, which caused 80 HW errors, then someone mentioned at bitcointalk that i should add more RAM, so i got 2GB instead of 512MB and the HW errors are gone.
So at least it’s doing [i]something[/i] with ram… -
[quote name=“Kevlar” post=“5219” timestamp=“1369199124”]
Let’s be clear about this: The amount of ram required is trivial. More ram won’t help. The amount of hashing a CPU can do is minuscule compared to a GPU. A i7 quad xeon should get about 24 Mh/s, a 5770 running on an i3 will get 250 Mh/s when tuned correctly. The bang for your buck is easily in favor of GPUs.Number one factor is CPU/GPU speed. That’s basically ALL that matters. When running scrypt, you MAY get a few extra Kh/s by overclocking your GPU ram if your running more than 600 Kh/s, but even then the limiting factor is going to be your GPU clock speed by far and away. When doing it on your CPU, you’re never going to max our your ram, nor your bus. Ever. The CPU will be pegged, and your DMA controller will be practically idle.
You see those little USB BlockEruptors? I bet then don’t have more than a few megabytes of ram on them. Notice I said megabytes, not gigabytes. Yet they outperform a 5770 with gigs of ram. It’s ALL in the Ops/second, not the storage size.
[/quote]Not entirely accurate. :P
SHA-256 is GPU intensive and OC’ing the hell out of your GPU pays dividends. In fact, when i mined BTC i under-clocked my RAM to save power and lost nothing in hashrate. We agree there.
Scrypt on the other hand is very memory intensive though its your video ram that takes a hammering. The GPU certainly helps but just OC’ing as fast it can it will usually result in a drop in hashrate. Tuning the RAM speeds results in significant increase (around 150KHs on a 7970). Notice i said tuning not OC’ing as high as possible. The GPU on my cards is stable 1150 for btc. With scrypt however i run at 1080 and tweaking the RAM to 1500 (from 1375) makes my 7970 fly.
GPU speed is not all that matters.
All that said, the quantity of video RAM is not that important but the number of stream processors is and that’s why [s]ATI[/s] AMD excels over nVidia for mining. System RAM, as long as you have enough to boot the OS and bit extra you’re good to go. 2G is a safe bet.
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Have 7970 both on 16x and 1x slot on same system.
theres no difference in hashing power between them.
mining doesnt require much bandwidth speed. 1x is more then enough.
gaming on the other hand you should have 8x or higher for highend cards -
[quote name=“svennand” post=“6074” timestamp=“1369412351”]
Have 7970 both on 16x and 1x slot on same system.
theres no difference in hashing power between them.
mining doesnt require much bandwidth speed. 1x is more then enough.
gaming on the other hand you should have 8x or higher for highend cards
[/quote]That’s correct, because with gaming you’re moving a butt-ton of textures in and out of memory, and performing matrix transforms on the geometry at your frame rate. With mining, you’re uploading code once, occasionally changing a few parameters, and getting any results it produces, so memory bandwidth is minimal from your bus to your GPU.
