Topic: Some advice on GPU's please? (Read 1619 times)

7950 is the most efficient, undervolt them and you get even more efficiency

Thanks very much, i will take your advice on the PSU's.

I have purchased 10 x powered risers that are 16x1x today for an awesome cost, i got them while they were still cheap

Sorry I didn't answer your question on the multiple PSU's. I don't think I would try that at all.  First you need a way to switch them all on at once and keep them running. 

Second you MUST use powered risers that isolate the 12 volt 8pin and 6pin PCI express power from the PCI-E slot on the mother board since they will be coming from different PSU's.  The problem is that it is highly unlikely that the voltage will be exact, so the power would flow from one to the other, not a good thing when they are on separate PSU's. 

This is the type of powered riser you would have to make http://forum.feathercoin.com/index.php?topic=2193.0  I actually think these risers should be used on any system, even with a single PSU.  It totally insures that you wont overload and blow your MB.  If somehow one of your 6 or 8 pin adapters come unplugged, the power will flow from the other cards down the powered risers, through the PCI bus and to the card without power...potentially blowing your MB.  Isolating the power avoids this.

I don't mind paying for quality and I don't think you can go wrong with a solid 1200+ watt PSU.  Seasonic is the only one I will use.  Plus they will have great resale value someday.

I'm sure others might feel differently. 

That MSI is a solid performer, my son actually has 12 of them in 3 rigs...they are a nice looking card! :-)  I'll post a pic if I can find it.

There is one thing we haven't solved with them and that is getting them running with 2 gpu threads.

The preferred config on a 280x is "gpu-threads" : "2" and "intensity" : "13" because you will get a great hash rate and your temps will be pretty low...all usually without OC'ing.
The other alternative is "gpu-threads" : "1" and "intensity" : "20" with maybe some OC'ing and higher temps (3°-4°C).  Both configs will yield close to the same hash rate, but GPU-threads is preferred if you can.

So on my son's MSI R9 280x cards we have not been able to have them run at the preferred config of gpu-threads 2.  I'm not saying it can't be done, we still have a few things to try, specifically hard coding the TC to a lower value than the card discovers natively.  I have Sapphire R9 280x and they run fine at gpu-threads 2.   We may end up flashing the MSI's to a different card bios, that may allow us to run the preferred config.

Also I have heard of a few fan failures on the MSI 280x, it seems that MSI may have a core deficiency in their fans...strange it is.

Good luck...hope this helps.

Hi Rudyo, I've spent a few hours tonight doing some reading and I think I am going to go for these:

http://www.shopblt.com/item/msi-computer-r9-280x-gaming-3g-3gb-900mhz-gpu/mstar_r9280xgaming3g.html#Availability

It works out at £188 a card which is around £70 off the RRP here in the UK, and they will only charge $200 ish for shipping all the way to my place here in the UK from the states, to me, its an absolute steal, unfortunately I have no idea how long they will be out of stock for and their pre-orders are already over-ordered. Otherwise I'm going to get the 7950s, because as much as i am 'not in a hurry', time is valuable in this game and I really want to ensure I am not wasting weeks / months for a delivery when I could have something equally as good for a slightly bit more £.

EDIT -> found some at an okay price in the UK - because of the quantity im sure i can get a better price:

http://www.uk.insight.com/en-gb/productinfo/graphics-cards/0002498451-00000001 - these pull 752 based on what im looking at on litecoin mining hardware comparison

And this -

http://www.uk.insight.com/en-gb/productinfo/graphics-cards/0002500308-00000001

Or the toxic

http://www.uk.insight.com/en-gb/productinfo/graphics-cards/0002498432-00000001

And this handsome one which has a minimum 732 based on litecoin mining hardware comparison too

http://www.uk.insight.com/en-gb/productinfo/graphics-cards/0002498381-00000001

I have a questions for you btw -



Is it even worth contemplating getting 1 PSU per card? Ie, 450W psu per card - my logic behind this is that 1. it is almost 1/2 the price of buying 2-3 1200+psu's of any decent quality, and 2, i think i will actually get better performance both energy wise and through the cards.

Baring in mind im UK Based, I could no doubt get you some 7950's but i doubt you would like the price once thats converted to $ friend!  I was looking at these as the alternative:

http://www.saverstore.com/product/20339145/RADEON-HD-7950-3GB-GDDR5-FLEX-PCI-E-2XDVI-HDMI-2XM-DP-OC-BOOST-IN

or

http://www.uk.insight.com/en-gb/productinfo/graphics-cards/0001866508-00000001?utm_source=Google+Shopping&utm_medium=Feed&utm_campaign=Feed&src=000093&&cm_mmc=Google+Shopping-_-Feed-_-Feed-_-Feed&gclid=COC24_OD37sCFQcTwwodjDcABg

In terms of stability and price/performance...YES!  What brand 7950 and are they new?  I started out with MSI 7950 Twin Frozrs, 12 of them (3 rigs of 4 each). They have never really had any issues other than some of the fans have crapped out (MSI's are sort of know for fan failures)  I've had to replace 4 fans, but most of these cards were used, so not too bad.  I have 2 rigs that haven't been touched in weeks, no reboots, nothing!  They just hash at a solid 640-660kh/s and run and run and RUN!  I never realized how good they were until I started messing with the 280x and then the 290x.  I spent (wasted...) a solid 3 days, probably 30+ hours tweaking and cajoling the dang 290's to hash.  Never again!

Depending on the price, I would buy either the 7950 or the 280x.  I don't like messing with dual PSU's and I will only use the Seasonic SS-1250XM PSU (unmatched PSU and out of stock EVERYWHERE) so I am pretty much limited to 4 cards per rig.  You may be able to unervolt the 7950 slightly and get away with 5 in a rig using the seasonic, but haven't tested that yet.  5 7950's would roughly match 4 280x in terms of output.

So do you know where I could buy a bunch of new 7950's?  I would buy a dozen right now if I could... 

lol alright, much appreciated for the wise words.

happy new years ;]

no i mean 290s complaints any brand outnumber all other gpus! and ditto xfx any card. actually i dont have a clue and therell doubtless be some bright spark out there with an xfx 290 who claims 999khs but save yourself some aggro

lol do you mean everyone complaining about those cards have XFX?

yeah rudyo knows what hes talking about. also the fact they're working on s.o. elses setup even if its identical to yours doesnt mean anything. also did someone say xfx theyre crap. am sick and tired of help me ive got a 290 threads here and on litecointalk. do not do it

Rudyo, I was just thinking about everything you've said and the fact you've experienced both the 7950 (which were the cards I was previously looking at) and the R9 290's....

Do you genuinely think buying 10x 7950's is a smarter move in terms of £ efficiency too / all round? ;/ Will save me about £1300 on the upfront cost of the GPU's too

Awww I plan on picking up 10 of them off a guy around 45mins from me, I think he also frequents this forum, and he said they are pulling 850khash each, he is also going to be showing this to me prior to purchasing them so i can confirm that this is the case. If not, I guess no go lol, but I don't doubt what hes saying and sincerely hope this to be the case!

Yep, Sapphire R9 290.  Windows 7, Windows 8.1, Linux, legacy drivers, beta drivers, WHQL Drivers, various SDK's, old cgminer, new cgminer...nothing seemed to help.  It was like they were possessed!  None of the tuning techniques that work so well on the 7950 and 280x series seemed to work.  Good riddance! :-)

Were you using saphires?

Good luck with the R9 290's, I found them to be a very fickle GPU as far as mining goes.  They didn't respond well to OC'ing and very small changes in any of the setup parameters seemed to make them less stable.  It felt like I was balancing on the head of a pin...while riding a unicycle!  I gladly sold all mine and went back to the 280x series which is a dream compared to the 290....IMHO.

Hi Miningguide, ty for reply, much appreciated.

I've actually managed to get a great deal with someone for 10 brand new r9 290's here in the UK.

Hi Sev,
The best value in terms of hash rate for money is actually the R9 270 @ $179/ea.
I recently switched the recommended graphics card in my 6 GPU  mining rig build guide from the 7950 to this card, due to the unavailability of the 7950.
You can stick six of these cards on one $230 1300 watt PSU for 2,700 Kh/s, which makes it an efficient and inexpensive rig all around.

With my very limited GPU mining experience I've found that mining cards with just 1 fan over the GPU simply isnt enough and leads to overheating issues far too frequently. I even have 2 120mm fans over one of my 1 fan video cards and it simply is not the same as having 2 fans built into the graphics card.

Hi Guys,

First of all, Happy New Years!

I wanted to get some expert opinion and feedback on what you think is the better option and the reason behind it

http://www.newegg.com/Product/ComboDealDetails.aspx?ItemList=Combo.1519177 - 4 of these

OR

Sapphire Radeon HD 7950 Graphic Card - 850 MHz Core - 3 GB GDDR5 SDRAM - PCI Express 3.0 - 6 of these

I'm interested to know which would be better simply because I have heard things like, for one, XFX are very unreliable and are prone to going boom when overheating, and I have always favoured Saphire anyway and have NEVER had an issue with them.

But above all, I am keen to know what you think in terms of hash rate / value for money?

Thanks in advance!

Sev