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The Radeon 7850 is an overclocking beast

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blastingcap said:
Not much difference. OC version is 920MHz. I'm assuming the non-OC edition is 860MHz. But they use the same cooler. Unless they binned the chips, I doubt they differ much. I got the OC edition only because it was the same price as the non-OC edition at the time.
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Well the OC version is €10 more. I know it's probably just blind speculation, but if there is even a *remote* chance they are binned it might be worth the €10 and just get the OC and possibly/likely get "better" chips. (Of course i am aware they are not binned for 1200mhz..means you could get a great OCer or a dud with any of those two).
 
flexy said:
Well the OC version is €10 more. I know it's probably just blind speculation, but if there is even a *remote* chance they are binned it might be worth the €10 and just get the OC and possibly/likely get "better" chips. (Of course i am aware they are not binned for 1200mhz..means you could get a great OCer or a dud with any of those two).
Click to expand...

Well at stock volts and stock fan profiles, I can't reach 1100MHz stable. I haven't had time to fine-tune things more finely (to like, say, 1095MHz or 1090MHz), so I just dropped 25MHz down to 1075MHz which I've been testing for something like 12 hours straight now at 100% load, and it's been 100% stable.

I'm sure with a more aggressive fan profile I can eke out a little more; and with a little overvolting (or water cooling; or both) a lot more. But I hate extra fan noise and overvolting for various reasons, and I'm too cheap to watercool, so I will leave that to more daring individuals. A 1075Mhz clock is still a 25% overclock and basically gets the 7850 to tie or even edge out a 7870@stock. 🙂
 
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blastingcap said:
TPU says at 19x12 resolution, the 7850 at stock is only 31% faster. With watercooling a 5850 can reach 1GHz and probably catch up to a stock 7850. And I've seen 5850s clocked up to 1150MHz before with liquid nitrogen, assuming linear scaling that's like 58% faster, even if not linear it's still some outrageous amount and probably a little faster than a 7850 in some situations (not tessellation or memory bandwidth limited situations).

Stock 5850 is 725Mhz core btw.
Click to expand...

VLIW5 scales poorly with more clocks, that's where GCN shines. I think I've said it like 3 times today, but this gen sucks at stock but is great when overclocking.
 
Yeah the 7850 is what I would get if I had that price range. AMD purposely lowered the clocks and voltage to hit lower tdp. Once you give it the right voltage, you get to really see what it can do. 1100mhz-1200mhz would be the sweet spot for me.

I would also like to see a review of whether gcn is more core limited, or memory bandwidth limited....
 
I'm tempted to get one of these. Just praying that when I do, it overclocks the way I want it to.
 
blastingcap said:
Well at stock volts and stock fan profiles, I can't reach 1100MHz stable. I haven't had time to fine-tune things more finely (to like, say, 1095MHz or 1090MHz), so I just dropped 25MHz down to 1075MHz which I've been testing for something like 12 hours straight now at 100% load, and it's been 100% stable.

I'm sure with a more aggressive fan profile I can eke out a little more; and with a little overvolting (or water cooling; or both) a lot more. But I hate extra fan noise and overvolting for various reasons, and I'm too cheap to watercool, so I will leave that to more daring individuals. A 1075Mhz clock is still a 25% overclock and basically gets the 7850 to tie or even edge out a 7870@stock. 🙂
Click to expand...

Have you upped the memory clock yet blastingcap?

The choice of 7850s here seems a bit limited. We have the 2 Sapphire models, the HIS, and the Gigabyte (most of which are covered here). At least a couple of folk have had issues with noisy Gigabyte 7850s (plus the cooler just looks flimsy to my eye, and I can find no reviews of the card). The HIS cooler (again, to my untrained eye) looks less capable than the rest, and I could find only one review. There are heaps of reviews of the OCd Sapphire, but I plumped for their stock-clocked model - looks like same cooler, but 10% cheaper.
 
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I am having an interesting conversation on another forum.

The main issue here is that the 7850 might be under-dimensioned in terms of voltage regulators and of course with its absent, second PCIE connector.

Short: Some people are speculating that it's not exactly "healthy" to overclock the crap out of this card towards GTX580 and beyond levels - while the onboard components are simply not made for the power draw under such such heavy loads.

Worst - what could happen that someone runs extreme apps like furmark etc...and the voltage regulators and the whole PCB would just "blow up"...

Mind you, this is pure speculation but there is definitely something to those concerns...

Can the 7850's power regulation components HANDLE such overclocks and the increased power draw - or could we sooner or later expect many overclocked 7850s basically blowing up because they are way to under-dimensioned for those resulting power requirements?

Mind you i am talking furmark and heavy, demanding gaming which would really tax the card and then it could show its weakness in being able to handle this.
 
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marlinman said:
Have you upped the memory clock yet blastingcap?

The choice of 7850s here seems a bit limited. We have the 2 Sapphire models, the HIS, and the Gigabyte (most of which are covered here). At least a couple of folk have had issues with noisy Gigabyte 7850s (plus the cooler just looks flimsy to my eye, and I can find no reviews of the card). The HIS cooler (again, to my untrained eye) looks less capable than the rest, and I could find only one review. There are heaps of reviews of the OCd Sapphire, but I plumped for their stock-clocked model - looks like same cooler, but 10% cheaper.
Click to expand...

Yes, see above in this thread. I went from 5GHZ to 5.8GHZ memory clocks with no hitches, and I wouldn't be surprised if it can do 6GHZ or higher with stability. I don't see the point in pushing memory up much higher than that, unless you have a truly monstrous core overclock.
 
flexy said:
The main issue here is that the 7850 might be under-dimensioned in terms of voltage regulators and of course with its absent, second PCIE connector.
Click to expand...
Even overclocked to 1050mhz it's only consuming 30w extra, and that's coming from a base of 860mhz. So if you add another 200mhz, you're probably only adding another 30w to the TDP for a total of 60w extra.

http://www.anandtech.com/show/5625/...-7850-review-rounding-out-southern-islands/18

Could that put the card beyond the PCI-E spec and beyond what it was designed for? Perhaps.

I think that a 1200mhz overclock at 1.2v is probably the limit of what is "safe". If you push it to 1.3v and 1300mhz you'll probably be pushing things too far IMO.

In my experience, it's not safe to push a GPU too hard. They can actually be damaged by overclocking them too far. I have seen friends lose their cards because of it.
 
flexy said:
I am having an interesting conversation on another forum.

The main issue here is that the 7850 might be under-dimensioned in terms of voltage regulators and of course with its absent, second PCIE connector.

Short: Some people are speculating that it's not exactly "healthy" to overclock the crap out of this card towards GTX580 and beyond levels - while the onboard components are simply not made for the power draw under such such heavy loads.

Worst - what could happen that someone runs extreme apps like furmark etc...and the voltage regulators and the whole PCB would just "blow up"...

Mind you, this is pure speculation but there is definitely something to those concerns...

Can the 7850's power regulation components HANDLE such overclocks and the increased power draw - or could we sooner or later expect many overclocked 7850s basically blowing up because they are way to under-dimensioned for those resulting power requirements?

Mind you i am talking furmark and heavy, demanding gaming which would really tax the card and then it could show its weakness in being able to handle this.
Click to expand...

This is similar to the 4850. I put some heatsinks on the VRMs on my 4850 and it's been running at more than 20% overclock for several years now. Still chugs along in my wife's machine until I get a 7850.

Before the VRM heatsinks, my MSI 4850 wasn't stabe at stock speeds in Furmark, let alone overclocked. You are correct that VRM is neglected by integrators on these midrange cards. The good news is that it's so neglected that all you need is a random heatsink and direct some air to it and you buy yourself huge margin.

Regardless, we'd already be seeing issues if there were major VRM issues with the 7850. They were apparent very early on with the 4850... but nobody had ever had VRM issues before, so people didn't know what it was. Now people know how a VRM issue manifests itself. Powertune limits keep you from creating fires by using Furmark, and overclockers with experience know that the VRMs are as important to cool as the GPU.
 
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SickBeast said:
Even overclocked to 1050mhz it's only consuming 30w extra, and that's coming from a base of 860mhz. So if you add another 200mhz, you're probably only adding another 30w to the TDP for a total of 60w extra.

http://www.anandtech.com/show/5625/...-7850-review-rounding-out-southern-islands/18

Could that put the card beyond the PCI-E spec and beyond what it was designed for? Perhaps.

I think that a 1200mhz overclock at 1.2v is probably the limit of what is "safe". If you push it to 1.3v and 1300mhz you'll probably be pushing things too far IMO.

In my experience, it's not safe to push a GPU too hard. They can actually be damaged by overclocking them too far. I have seen friends lose their cards because of it.
Click to expand...

http://www.techpowerup.com/reviews/AMD/HD_7850_HD_7870/24.html

Peak load is 96 watts for the 7850 for Crysis 2 (I'm going to ignore stuff like Furmark) for stock clocks and fan. Let's say that 75 watts of that is the GPU and the rest is the rest of the board, including memory and fans.

Overclocking to 1.2GHz would be roughly 40% overclock and translate to a total board draw of about 105, plus overclocked memory and fans might add about 30 more watts. That's still just 135 watts at stock voltage.

Of course, almost nobody can hit 1.2GHz at stock voltage. Even a mild overvolt of 5% (1.075 -> 1.12875 volts) translates to 10.25% more power usage since power varies by the square of voltage. That translates to 149 watts, or right at the 150W limit.

So for safety reasons, I wouldn't try to chase 1.2GHz using more voltage than 1.13 volts. Just be happy with whatever overclock you can get at that point, even if it's only 1.15GHz or whatever. Not worth ruining your card over 1-2 more frames per second.

Now, if you want to use average and not peak numbers, that's going to give you a little more room but you will go over spec occasionally. 87W average, let's say 70 watts from the GPU. If you overclock 40% and overvolt by 10% that gives you 119W on the GPU, add back about 30W for overclocked memory/fans and you are sitting at 149W. An overvolt of 10%, at least for my card, is 1.075*1.1 = 1.1825V.

(Note that the CCC panel has -50% to +50% power limitation, and if we take "0" to mean 150W, then +50% = 225W.)
 
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blastingcap,

cool name..that's exactly what i had in mind 😉

Anyway..i just read about this AMD feature "PowerTune" and how it supposed to be a mechanism to keep the card(s) within TDP spec...i wonder how this comes into play?

Is this "powertune" a software solution (done within the CCC) or is this done in hardware? Most importantly...is it actually "good" or "bad" in regards of our subject of overclocking the 7850?

"Good" in a sense that it can help keeping the card safe (ie. the VRM wouldn't blow up in your face)...or "bad" in a sense that someone could clock their cards as high as they want but powertune will sooner or later clock down the cards as a safety measure? (And the people claiming all those high clocks are actually fooled because they didnt take powertune into account?)
 
flexy said:
I am having an interesting conversation on another forum.

The main issue here is that the 7850 might be under-dimensioned in terms of voltage regulators and of course with its absent, second PCIE connector.

Short: Some people are speculating that it's not exactly "healthy" to overclock the crap out of this card towards GTX580 and beyond levels - while the onboard components are simply not made for the power draw under such such heavy loads.

Worst - what could happen that someone runs extreme apps like furmark etc...and the voltage regulators and the whole PCB would just "blow up"...

Mind you, this is pure speculation but there is definitely something to those concerns...

Can the 7850's power regulation components HANDLE such overclocks and the increased power draw - or could we sooner or later expect many overclocked 7850s basically blowing up because they are way to under-dimensioned for those resulting power requirements?

Mind you i am talking furmark and heavy, demanding gaming which would really tax the card and then it could show its weakness in being able to handle this.
Click to expand...

Some cards are built just like thier 7870 big brothers like XFX for example. Same PCB same 2/6 pin/same cooler etc. Perhaps that's the way to fly if that's the case?
 
Zebo said:
Some cards are built just like thier 7870 big brothers like XFX for example. Same PCB same 2/6 pin/same cooler etc. Perhaps that's the way to fly if that's the case?
Click to expand...
I read somewhere that the initial batch of 7850s were built on the 7870 PCB but that the newer versions were going to be cheaper custom PCB.
 
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flexy said:
Is this "powertune" a software solution (done within the CCC) or is this done in hardware? Most importantly...is it actually "good" or "bad" in regards of our subject of overclocking the 7850?

"Good" in a sense that it can help keeping the card safe (ie. the VRM wouldn't blow up in your face)...or "bad" in a sense that someone could clock their cards as high as they want but powertune will sooner or later clock down the cards as a safety measure? (And the people claiming all those high clocks are actually fooled because they didnt take powertune into account?)
Click to expand...

It's software but I think it's hackable? I could be mistaken.

Good and bad. I'd say probably more good than bad, on the balance.

http://www.anandtech.com/show/4061/amds-radeon-hd-6970-radeon-hd-6950/7 (and the following page, at http://www.anandtech.com/show/4061/amds-radeon-hd-6970-radeon-hd-6950/8 ) should answer your questions more fully.

Edit: apparently I misunderstood the baseline for Powertune, according to http://www.anandtech.com/show/4061/amds-radeon-hd-6970-radeon-hd-6950/9 so I guess +50% on the CCC slider means 150 * 1.5 = 225W
 
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Yes i am a little confused also, in particular if we assume there is a "safe" threshold for a TDP, say for our card 150W..why should there be a slider to exceed this?

Could we assume that the range they show in CCC, say +/-20 would still be "safe" to use then?

The other question..if i look at powertune as kind of a safety measure (?), ESPECIALLY in situations like furmark or with other (what they call) outlier apps - i mean this would be exactly what we want to prevent the hardware getting fried in such extreme situations...but would it really effectively prevent VMRs etc. blowing..since (as far i can tell now)...isn't this more a matter of extreme short and SUDDEN spikes...wouldn't the board "blow" before this has even a chance to activate and throttle?

(I blew a PSU once by running furmark, just as a side-note)
 
blastingcap said:
TPU says at 19x12 resolution, the 7850 at stock is only 31% faster. With watercooling a 5850 can reach 1GHz and probably catch up to a stock 7850. And I've seen 5850s clocked up to 1150MHz before with liquid nitrogen, assuming linear scaling that's like 58% faster, even if not linear it's still some outrageous amount and probably a little faster than a 7850 in some situations (not tessellation or memory bandwidth limited situations).

Stock 5850 is 725Mhz core btw.
Click to expand...

Mine can hit 1ghz on air, but the performance scaling is not perfect. Assume a 5850 can reach a stock 7850 performance.. 7850s can do >40% OCs now with vcore mods available. It will still be heaps faster and in all games not just where VLIW excels at, and using a lot less power (5850s with vcore OC uses a lot of extra power!).
 
The XFX one is the one which *should* have sufficient power regulation components since it's the one with two power connectors. Although i have read some reviews where they say the fans of the XFX are weak and the cooling itself is lacking.

But i am really hesitant thinking about the card (AT THIS POINT) doing heavy overclocking, without really knowing how the caps and VMRs would handle that increased load. You don't want to draw 250W or so knowing the circuit can only 150W. There is still some "real life" experience we need.

In other words: Are people achieving those massive overclocks *without* their cards basically "blowing up" once they are brave enough to run furmark etc... guys that's really an issue i think...
 
Alaa said:
We need some MILITARY CLASS components here please!
Click to expand...

The problem is that "military class components" and budget card for +/- $200 don't really go together. The same with the XFX 7850 which look VERY interesting to me, but defies the purpose because of the increased costs.

As a overclocker, there is ONE rule:

If you overclock...you get solid and good quality components. Because you want to make sure your hardware can handle the overclocks, you want to get the best our from your hardware.

So..there is a big discrepancy looking at the budget 7850 cards, mainly for the reason to overclock the **** out of them...but then realizing the cards are not exactly built for this purpose.

With one power connector, they can draw 75W from the 6 pin power connector, and another 75W from the PCIE connector itself, which makes a max. of 150W total. There is no way around this.

ANYTHING beyond that just screams for problems.

This is like wanting to build an overclocker's rig an shooting for 40% or 50% overclock...but having no heat sinks and fans.

UNLESS...people can show that even in the most extreme scenarios (benchmarks etc.) the 7850 will NOT draw more than 150W +/- some which would still be tolerable in terms of hardware...
 
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