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Author Topic: 2 x 5850's Overclocking..  (Read 1549 times)
makko
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July 28, 2011, 07:59:04 PM
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Hi Guys,

Firstly I have a stock 5850 725/1000 running @ (880/300/72Deg/Cel) (GPU/MEM/TEMP) which is giving me ~350 MH/s, I think this is good what you guys think.

Then my second 5850
< http://cgi.ebay.ie/ws/eBayISAPI.dll?ViewItem&item=250854976781&ssPageName=ADME:X:RTQ:IE:1123 >
is a beauty I think (to be installed this weekend)..

The guy had it running @ 1000/1250 (GPU/MEM) with really good temps. I'm just wondering what way I should overclock it to get best hashing rate. I'm a complete n00b to OC so don't freak out if this is way off (  Undecided ) But, i'm thinking I can underclock the mem and (maybe increase the GPU) to get a great hashing rate. I'd like to see at least 400 MH/s from this card.

If I underclock the memory is ok to clock the GPU even more or is that dangerous? Do I need to overvolt then and is that high risk?

NOTE: I'm using TRIXX for OC and powering with a TX750W Corsair PSU, Intel Core i5 3.2Ghz.

PS. What do you guys think of the second modded card, I think it looks pretty sick, and bought it for 100 euro whereas the stock one cost me 169 Euro (New) Shocked


Any feedback appreciated, cheers  Wink

Too lazy for a fancy sig.. Tongue
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mastergamer
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July 28, 2011, 08:52:06 PM
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you bought this card with that cooler for 100 euro  Shocked

thats a crazy price.
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July 28, 2011, 08:55:37 PM
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you bought this card with that cooler for 100 euro  Shocked

thats a crazy price.


140 EUR = $200 USD thats not too bad depending on how good that cooler works, if you look around people are selling them for 170, some including shipping some not.
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July 28, 2011, 08:58:27 PM
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Hi Guys,

Firstly I have a stock 5850 725/1000 running @ (880/300/72Deg/Cel) (GPU/MEM/TEMP) which is giving me ~350 MH/s, I think this is good what you guys think.

Then my second 5850
< http://cgi.ebay.ie/ws/eBayISAPI.dll?ViewItem&item=250854976781&ssPageName=ADME:X:RTQ:IE:1123 >
is a beauty I think (to be installed this weekend)..

The guy had it running @ 1000/1250 (GPU/MEM) with really good temps. I'm just wondering what way I should overclock it to get best hashing rate. I'm a complete n00b to OC so don't freak out if this is way off (  Undecided ) But, i'm thinking I can underclock the mem and (maybe increase the GPU) to get a great hashing rate. I'd like to see at least 400 MH/s from this card.

If I underclock the memory is ok to clock the GPU even more or is that dangerous? Do I need to overvolt then and is that high risk?

NOTE: I'm using TRIXX for OC and powering with a TX750W Corsair PSU, Intel Core i5 3.2Ghz.

PS. What do you guys think of the second modded card, I think it looks pretty sick, and bought it for 100 euro whereas the stock one cost me 169 Euro (New) Shocked


Any feedback appreciated, cheers  Wink

Going back to the original post, yes you can under clock the memory for bitcoin mining with no problems, actually suggested the lower the better so less heat is generated on the card. 400 Mhashs from a 5850 is going to be interesting  I run mine at 900 / 300 but its already running too hot for my taste 75C.

I would imagine the next step is to over voltage the card and push it to say 1100 you should get close 400 Mhashes, you will have to look around the forums to see whats the safest yet best voltage to overclock to achieve your goal.
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July 28, 2011, 09:01:03 PM
 #5

you bought this card with that cooler for 100 euro  Shocked

thats a crazy price.


I believe that was a 'good luck fitting this in your machine' price Wink

The memory and GPU clocks are separate, you can tweak them in either direction individually without effecting performance of the other (much).

If his stats are accurate and he's getting 1000/1250 gpu/mem @ 80C, you can probably clock to 1000/400 easily, and your temps should be amazing with the downclocked RAM.

The ebay posting mentions he cooled the VRM, but it's a common misconception that VRM (voltage regulators) and VRAM (video random access memory) are the same thing - they're not.  It appears that he did stick sinks on the VRAM.  

This isn't a bad thing at all, but you may need to be careful when clocking very high - if that cooler is doing it's job it should be keeping everything pretty frosty and running with low fan speeds - which can mean your VRMs aren't getting enough airflow and may heat up.

The fix is easy, just set your fanspeeds manually >= 60% or so.

This will be especially important if you want to overvolt the card for more stability at higher clocks.


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makko
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July 29, 2011, 01:04:24 PM
 #6

Hey guys,

Thanks for the feedback.. looks like a good deal with the modded card then. BTW, I'm putting this in a 4U rackmount case so space shouldn't be an issue SmileySmiley
Link: http://www.xcase.co.uk/X-Case-RM413-LCD-Pro-p/case-xcase-rm413pro.htm

When I put it in i'm gonna UC the memory then OC GPU to about 1000 Mhz and see how I go.. I'll have to look into Overvolting before I touch that though.

Also, what's the best way of checking the stability when hashing? stales vs accepted?

Thanks.

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catfish
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July 29, 2011, 05:56:31 PM
 #7

That card is a mad gamer person confection Smiley Insane, just insane.

It appears that the big heatpipe and cooler sticking out the back of the card is for the memory, not the core. If it's for the VRMs then it would actually be useful for mining, whereas if it's just on the memory chips themselves then it's not any use for mining.

I clock my memory at 275 MHz. Normally the minimum is 300 MHz but under load the cards run at 1,000 MHz (base - if the memory is DDR4 then the total bandwidth will be 4,000 MHz, but forget that for a moment because mining is NOT heavy on memory bandwidth).

This cooler has let the original owner run his memory clock at 1,250 MHz - for games, this will be a worthwhile mod. Won't help with mining though, and the memory runs very cool regardless if you clock down to around 300. The standard cooler is built for 1,000 MHz memory clock. Running his mental memory clock will just draw a LOT more power and create heat - without increasing your hash rate.

With the latest modded OpenCL kernels, hash rate is pretty much linearly proportional to number of stream processors and the clock they run at. So with the same card, it is ALL about core clock rate.

In this case, you've got a card that has a guarantee that it runs happily at 1,000 MHz core clock. That's with the memory overclocked too! So putting a large underclock on the memory will reduce power consumption and heat - whether it allows greater headroom with the core clock is for you to find out!

I can give some exact numbers here - with a standard 'old' Sapphire 5850 (with the 5 fat copper heatpipes), running 999 MHz core and 275 MHz memory netted me a fat 408 Mhash/s with temps below 70˚C. This card may be one of the lucky ones, because I've got 3 other 5850s and none will clock this high.

The big question is whether the additional vertical heatpipe cooler is cooling the VRMs and not just the RAM chips. If it's cooling the VRMs... then you are in luck, even if just for longevity purposes. Even when an overclocked card is running 60-70 ˚C reported temperature, the VRMs themselves often are well over 100˚C. Cool those - and the card will last much longer. You may be able to overclock the card further...

However I've found that some of my cards simply won't overclock beyond a certain speed even though the card is well within thermal tolerances. It's the luck of the draw regarding the quality of the GPU wafer.


I'd say that you'd definitely get more than 408 Mh/s simply because the seller claims it's stable at 1,000 MHz core clock, and I know what I can achieve with a 5850 at that clock!

BTW - my figures are at standard voltages. Overvolt at your peril. Though, again, if that big heatsink is protecting the VRMs, then overvolting is safer. But I'd do more research into how the *other* components on the card react to overvolting before touching those options. Remember, if all you're after is 400 Mh/s - you've got it, at core clock. No need to overvolt!

Regarding stability - just run the damn miner flat out. If you're clocking past stability, then the kernel will crash, the card will stop accepting work, the GPU core temperature will drop and the mining software will stop returning work. I just watch the temperature for an hour, and if it steadily heads to 90 degrees then it's too hot - and if it rises before falling dramatically, then it's just crashed and I need to reboot the box. DO NOT COMMIT YOUR CLOCK SETTINGS UNTIL YOU ARE *SURE* THE CARD CAN SUSTAIN THEM! Otherwise, the card may crash on boot and you'll have all sorts of fun.

...so I give in to the rhythm, the click click clack
I'm too wasted to fight back...


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Zagitta
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July 29, 2011, 10:30:04 PM
 #8

I'm 99% sure the cooler on the back is for the VRMs because i remember reading about it somewhere... anyway with those coolers you should have no problem reaching the core's clock limit which i guess is around 1050-1100 mhz when mining (asuming you underclock the memory to 300 mhz or similar)
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July 29, 2011, 10:38:24 PM
 #9

I run mine at 1020/300 and it stays around 71C with a table fan blowing at it.  That's good for about 412 MH/s.  I've pushed it to 1040MHz but my worker locked up after a few hours.  But yeah, 350 MH/s is wayyy too conservative for these cards.

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ahitman
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August 19, 2011, 06:59:46 PM
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How did your overclocking go? Did you do any voltage tweaks? How many hashes/s are you getting?
makko
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August 19, 2011, 10:21:52 PM
 #11

Hi There,

Thanks for posting I had been meaning to post back with my results..

Well, with one card running @ stock gives me 329 MH/s

The second uber modded card was giving me around 370 at 940/300 Mhz @1099 volts it ran alright.. but would crash randomly after a few days to a week. As the miner was unattended in windows I decided to clock back to 860/300 @1088volts.. this is giving me 341 MH/s

I plan on taking out the uber card to put in my personal desktop for gaming. My OS for general use when not gaming is Ubuntu so i'll be able to overclock it in that and monitor everything closely.. when I get that setup i'll be squeezing out all the MH/s that this baby has to offer..

@ahitman How you getting on? What kinda setup you running?

Smiley

EDIT: Too lazy to upload pic.. how can I attach it? Tongue

Too lazy for a fancy sig.. Tongue
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August 19, 2011, 11:30:17 PM
 #12

I'm surprised at the instability - it looks like a 'monster' card. My bog-standard old Sapphire is still running 24/7 at 403 MH/sec using 990 MHz core clock.

However I notice that if I use that particular card to connect a display to, the additional load added by Compiz (my dedicated miners all run Linux - currently Ubuntu natty) can lock the card up. If the card is DISPLAY :0.2 (anything but :0.0) then it's not touched by X and can devote its entire processing to OpenCL mining.

I'd imagine that Compiz effects whack memory bandwidth, whereas mining doesn't (hence why we underclock memory on mining cards). I'm not a Linux über-guru (though reasonably competent) - however I *am* a Mac OS X hacker, and Compiz is suspiciously similar to Quartz Extreme (in terms of functionality). And QE hammers GPU memory bandwidth by making every window a texture so all sorts of fancy compositing / transparency effects can be achieved.

Turn Compiz off and this may not happen. Turning X off altogether makes mining difficult Wink

Re: Windows - I don't use Windows so don't know if similar desktop-drawing processes would limit the mining performance of a given card. AFAIK, the Aero desktop is Microsoft's compositing-engine answer to Quartz Extreme and Compiz, so if you're using this, it could be a case of 'same sausage'...


Put it this way - even the lamest 5850 cards I own (one Sapphire 'extreme' and one XFX 'Black Edition' - both lame) croak at 900 MHz core clock. Note that I use 275 MHz memory clock, and these cards are in open frame rigs, getting no hotter than 65˚C or so. Using the 17th July edition of phatk and phoenix, I get a steady 370 MH/sec from 900 MHz. I've got three different types of 5850 card, and the weakest of them all can still manage 900 MHz and 370 MH/sec, so IMO you should aim for that really. Any less seems *very* conservative to me - remember that I do NOT fiddle with voltage, all cards are standard.

Have you set the fan speed to maximum? Also consider using a more optimised OpenCL kernel, if your miner and OS setup allows. If I can get 370 MH/sec from 900 MHz core clock on two different brands of 5850 card consistently... but you need 940 MHz core to get the same hash rate, then I must have a more efficient OpenCL kernel. As stated, I use the 17th July phatk kernel - later 'optimisations' are slower, in my experience on my range of cards (5670, 5770, 5830, 5850) - perhaps Diapolo is now optimising for the 6xxx series of Radeon cards, but my testing clearly shows the 2011-07-17 kernel to be Boss Cat for my 5xxx series Radeons.

...so I give in to the rhythm, the click click clack
I'm too wasted to fight back...


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