6950 Dirt 3 ED overclocking

G

grandpatzer

Gawd
Joined
Feb 24, 2010
Messages
641
I recently got 2x Sapphire 6950 Dirt3 dual fan cards.

Because I "only" have HX650 which is 650w I decided to put CPU vcore to 1.25v and stock speeds.

Ive so far taken baby steps, I looked at the [H] review of 6950 Dirt3 OC and decided to push both cards to 875/1325 with 1.125v.

The OC is so far so good, only ran Combustor 4minutes, Heaven 2.5 DX11 and AvP I ran at 5900*1080.

I'll game some and hope the cards are stable at these levels.

If I feel brave I might even up the speed a bit more and GPU vcore.
 
You'll be fine with a bit of an overclock, I'm running my i5 750 at 1.35V which is well above stock, and two HD6970s, and I'm only pulling about 630-650W max in games, but I do reach around 700 in furmark. If you're going to overclock the cards be careful, because obviously the X4 965 uses a lot more power to start with, especially if it's a 140W TDP version instead of the newer 125s. You should be able to overclock the cards fine with the CPU at stock, as even if you breach 650W Corsairs are usually good enough not to shut down until about 10% over (so around 710-720W, possibly higher), but in the long run if you want your CPU overvolted again I'd look into getting something like an AX 850 as an upgrade.
 
I think you'll be fine leaving your CPU overclocked as well. I'm running an i7 970 @ 4.2GHz with two reference 6950's unlocked to 1536 shaders and overclocked to 920/1425/1.25v, all on a Seasonic X-650 PSU. Your HX650 isn't quite as good but should still be fine since your 6950's aren't unlocked.

Just avoid stressing everything at 100% simultaneously, i.e. Furmark + Intel Burn Test.
 
samuelmorris said:
You'll be fine with a bit of an overclock, I'm running my i5 750 at 1.35V which is well above stock, and two HD6970s, and I'm only pulling about 630-650W max in games, but I do reach around 700 in furmark. If you're going to overclock the cards be careful, because obviously the X4 965 uses a lot more power to start with, especially if it's a 140W TDP version instead of the newer 125s. You should be able to overclock the cards fine with the CPU at stock, as even if you breach 650W Corsairs are usually good enough not to shut down until about 10% over (so around 710-720W, possibly higher), but in the long run if you want your CPU overvolted again I'd look into getting something like an AX 850 as an upgrade.
Click to expand...

Are you pulling 630-650w from the wall?
Incase efficiency is 85% that means 535w-552w is the power draw on components.

When I played Dirt3 when there is no ingame sound I can hear the PSU giving buzzing noise or maybe the PSU fan clicking.
^^^^^Can also be heard when starting Kombustor from PSU.

Mine is C3 125w
 
no 630-650 from the PSU, 700-750 from the mains (and it's a 90% unit, since I'm on 230V mains).
You might just be hearing coil whine from the graphics cards, it's not necessarily the PSU (though the PSU will buzz a bit)
 
samuelmorris said:
no 630-650 from the PSU, 700-750 from the mains (and it's a 90% unit, since I'm on 230V mains).
You might just be hearing coil whine from the graphics cards, it's not necessarily the PSU (though the PSU will buzz a bit)
Click to expand...

Bad news for me then, I was planning to OC closer to 6970 speeds but looks as it's not going to be possible without PSU change for me.

The 1.35v I5 how high is the TDP would you think?


I currently have undervolted my 125w cpu to 1.25v and 3.40ghz so I think it is 115w TDP.
 
I just picked up one of these cards to play with. I am pretty pleased with the OC actually. 970 core 1380 Memory @ 1.18v and will loop Heaven/Metro2033 demo's for 30 minutes each with no issues at that speed. Since they have the bios switch, I tested to see if mine would unlock. Alas, it would not, but still with the OC it runs very well.

I think two of them on your PSU should be fine, but I would be leary of OC's. they can really start gobbling up wattage once OC'd.
 
I read the [H] review of this card, when OC it to 1.125v it increased 17w in BF2.
This mean going from 1.100 to 1.18 will give 54.4w more than stock Dirt 3 ED.

The stock Dirt3 ED is 40w more than stock ref 6950.
Ref 6950 TDP is 158w, so Dirt3 ED TDP stock is 198w,

OC to 1.18v gives 198 + 54.4w= 252.4w, so 2 cards is 504.8w.

that leaves 145.2w for CPU and other components, too little...

Next step is most likely to sell the HX650 and buy a 850w PSU.
 
grandpatzer said:
Bad news for me then, I was planning to OC closer to 6970 speeds but looks as it's not going to be possible without PSU change for me.

The 1.35v I5 how high is the TDP would you think?


I currently have undervolted my 125w cpu to 1.25v and 3.40ghz so I think it is 115w TDP.
Click to expand...

I've had it quoted around the 180-200W mark, which seems about right given the change in system load when I run something like OCCT on the CPU.

You can't just sum the wattages like that grandpatzer, because the card will run at a different voltage to start with, so the increase will be less than 54W for a card that's already overvolted (and in any case, you can't linearly add these increases, you have to consider they are exponential!)
 
samuelmorris said:
I've had it quoted around the 180-200W mark, which seems about right given the change in system load when I run something like OCCT on the CPU.

You can't just sum the wattages like that grandpatzer, because the card will run at a different voltage to start with, so the increase will be less than 54W for a card that's already overvolted (and in any case, you can't linearly add these increases, you have to consider they are exponential!)
Click to expand...

I'm not sure I follow what you mean according [H] TDP review of this card the Load difference to stock card is 40w.

Now the ref stock has a TDP of 150w, however with powercontrol it goes up to 200w.
I have no Idea what that really means, so with powercontrol and 1.10v the reference card gives 200w.

^^^^^^ In that case my Dirt3 dual fan gives 150w +40w at 1.10v and powercontrol disabled.
The guru3d has 6950 at 158w TDP, so my card pulls 200w at stock and PC disabled.

According the [H] TDP review of this card The TDP is 17w more at 1.125v and 875/1325.

So with PC disabled I should be pullin 220w/card in BF2 with 1.125v@875@1325
 
Have a think for a minute - why is the Sapphire HD6950 drawing 40W more? It's still an HD6950 underneath.
The reason for it is because the HD6950 is already overvolted.
If you overvolt your card to 1.125V you're looking at 17W extra. However, the Sapphire card is already overvolted beyond that point, so you wouldn't need to overvolt it again.

APrcm.png

Here is a rudimentary diagram of the voltage levels.
YELLOW - The stock voltage of a normal HD6950.
GREEN - The 1.175V setting you're looking at overclocking your card to.
BLUE - The voltage the Sapphire card uses, out of the box.
PURPLE - The voltage the Sapphire card would use if you overvolted it further.

If you were to get the Sapphire card to 1.175V, you'd actually be lowering the voltage of the card, and thus reducing your power consumption, because you'd be going from BLUE to GREEN.
Only if you wanted to overvolt the Sapphire card beyond its normal rating even further, from BLUE to PURPLE, would you be adding more power.

Additionally, you can't just add the numbers up like this ("Overvolting my card 0.025V adds 17W, so if I overvolt a different card, it'll also add 17W") because increased wattage is exponentially related to voltage.

Think about it from a simple perspective. Imagine a 100V electrical supply, with a 100W light bulb. To draw the 100W, this light bulb must use a current of 1A, because 100V*1A = 100W. As you increase the voltage though, you increase the current too.
Say you now put 120W through this light bulb, it wouldn't become 120W, it'd become 120*1.2=144W. It's an exponential increase.
This isn't an ideal analogy because PC hardware doesn't follow ohm's law perfectly, but it summarises the point I'm trying to make. if you increase the voltage a certain amount, you'll get a power increase. If you increase it the same amount again, you'll get a much bigger power increase than before. For this reason, you can't add the difference you got with one card, to the normal power draw of another. That's not how it works.

Hopefully this makes some sense.
 
samuelmorris said:
Have a think for a minute - why is the Sapphire HD6950 drawing 40W more? It's still an HD6950 underneath.
The reason for it is because the HD6950 is already overvolted.
If you overvolt your card to 1.125V you're looking at 17W extra. However, the Sapphire card is already overvolted beyond that point, so you wouldn't need to overvolt it again.

APrcm.png

Here is a rudimentary diagram of the voltage levels.
YELLOW - The stock voltage of a normal HD6950.
GREEN - The 1.175V setting you're looking at overclocking your card to.
BLUE - The voltage the Sapphire card uses, out of the box.
PURPLE - The voltage the Sapphire card would use if you overvolted it further.

If you were to get the Sapphire card to 1.175V, you'd actually be lowering the voltage of the card, and thus reducing your power consumption, because you'd be going from BLUE to GREEN.
Only if you wanted to overvolt the Sapphire card beyond its normal rating even further, from BLUE to PURPLE, would you be adding more power.

Additionally, you can't just add the numbers up like this ("Overvolting my card 0.025V adds 17W, so if I overvolt a different card, it'll also add 17W") because increased wattage is exponentially related to voltage.

Think about it from a simple perspective. Imagine a 100V electrical supply, with a 100W light bulb. To draw the 100W, this light bulb must use a current of 1A, because 100V*1A = 100W. As you increase the voltage though, you increase the current too.
Say you now put 120W through this light bulb, it wouldn't become 120W, it'd become 120*1.2=144W. It's an exponential increase.
This isn't an ideal analogy because PC hardware doesn't follow ohm's law perfectly, but it summarises the point I'm trying to make. if you increase the voltage a certain amount, you'll get a power increase. If you increase it the same amount again, you'll get a much bigger power increase than before. For this reason, you can't add the difference you got with one card, to the normal power draw of another. That's not how it works.

Hopefully this makes some sense.
Click to expand...

thanks for the explanation, I'll look at it careful later and think what it all means.

All the reviews I read never mention this, they just say that they are supprised that the card pulls 40w more just as it is only one fan more.

Everyone that make review of this card say it must be because the components on this non ref card draw more power nut no mentioning of Vcore and power usage.
 
Well that's exactly it, think from a technological perspective, what uses 40 watts of power. That's a hell of a lot in real world terms. An entire Nintendo Wii doesn't even use half that much, while playing a game. Extra fans, slightly less efficient voltage regulation might add perhaps 10-15W at most on a card like this, but 40? This suggests the card has been overvolted, and if you read the article, they confirm that it has been overvolted.
 
samuelmorris said:
Well that's exactly it, think from a technological perspective, what uses 40 watts of power. That's a hell of a lot in real world terms. An entire Nintendo Wii doesn't even use half that much, while playing a game. Extra fans, slightly less efficient voltage regulation might add perhaps 10-15W at most on a card like this, but 40? This suggests the card has been overvolted, and if you read the article, they confirm that it has been overvolted.
Click to expand...

So when I OC it to 875/1325 and put the vcore to 1.125v I actually Overclocked and undervolted the card?

my interpretation of the review is that the Vcore in Trixx does nothing because according the review the TDP increased 17w at 1.125v and 875/1325

If the card truly was undervolted it should decrease in TDP?

Edit --> but GPU-z shows 1.100v when the card is stock with no OC apps open, so still the card is not overvolting the vcore but other components on card then?

Edit2 --> I reread the conclusion of the review, increasin Vcore helped overclocking so the 6950 Dirt3 dual fan other components are overvolted in that case but not the vcore.

So in that case the TDP is 200w stock and when overclocking vcore to 1.18 one can expect TDP of 250-260w
 
Last edited:
As it stands no. It was my impression the Toxic card used a very high voltage, but according to the [H] review, I was mistaken, it uses 1.100V. Still higher than the normal 1.050V for the HD6950, but not as high as the quite excessive overvolt you're looking at with 1.175.

Generally speaking, I'd anticipate something roughly along these lines:
1.050V standard - 170W TDP
1.100V normal card - 195-200W TDP
1.100V Toxic card - 210W TDP
1.125V normal card - 220W TDP
1.125V Toxic card - 230W TDP
1.175V normal card - 240W TDP
1.175V Toxic card - 250W TDP

This of course assuming the powerplay limits are not breached.
I am using 170W as a base and not 200W, as this is what the card typically draws from systems, from what I've seen of benches. Pulling the 200W figure is normally impossible without overclocking first (or flashing to a 6970).
 
samuelmorris said:
As it stands no. It was my impression the Toxic card used a very high voltage, but according to the [H] review, I was mistaken, it uses 1.100V. Still higher than the normal 1.050V for the HD6950, but not as high as the quite excessive overvolt you're looking at with 1.175.

Generally speaking, I'd anticipate something roughly along these lines:
1.050V standard - 170W TDP
1.100V normal card - 195-200W TDP
1.100V Toxic card - 210W TDP
1.125V normal card - 220W TDP
1.125V Toxic card - 230W TDP
1.175V normal card - 240W TDP
1.175V Toxic card - 250W TDP

This of course assuming the powerplay limits are not breached.
I am using 170W as a base and not 200W, as this is what the card typically draws from systems, from what I've seen of benches. Pulling the 200W figure is normally impossible without overclocking first (or flashing to a 6970).
Click to expand...

My card is not the Toxic which has 8pin connector and factory OC.

Mine is a dual fan sapphire with only 6 pin connectrors and no factory OC.

I was under impression all 6950 are 1.1v maybe I'm wrong, I agree that atm my card is pulling 200-230w at 1.125v.
 
jhatfie said:
I just picked up one of these cards to play with. I am pretty pleased with the OC actually. 970 core 1380 Memory @ 1.18v and will loop Heaven/Metro2033 demo's for 30 minutes each with no issues at that speed. Since they have the bios switch, I tested to see if mine would unlock. Alas, it would not, but still with the OC it runs very well.

I think two of them on your PSU should be fine, but I would be leary of OC's. they can really start gobbling up wattage once OC'd.
Click to expand...

That's a great oc. What are your scores before and after oc?
 
I accidentaly in trixx had card at 1.100v and 875/1325 and it was stable gaming 1hour of Dirt 3.

twice there was darkening of screen for wery short time maybe 0.2-0.3seconds, no Idea if it was because the game or if the GPU's needed more vcore.
 
You mean you did not test those clocks before bumping the voltage yet you worry about power consumption?

Increase the clocks until you freeze or artifact in games then increase the voltage. Not do both together.
 
IAMEVIL said:
That's a great oc. What are your scores before and after oc?
Click to expand...

Just a couple quick examples: OC at 985/1395 @1.18

3dMark11 (default settings):
Stock - 5163
OC'd - 6077

Metro 2033 benchmark 2560x1600, DX11, DOF off, AAA, AF16x, High Quality
Stock - 38.67 fps Avg
OC'd - 44.59 fps Avg
 
Orinis said:
so i take it these carsd oc much better than 560ti's?
Click to expand...

I wouldn't say they overclock better but since the 6950 is faster out of the gate at the end of the overclocking the best you get with a 560ti is slightly over GTX 570 stock performance.

A 6950 such as this one which uses the sapphire vapor x cooler can exceed 6970 stock speeds by quite a bit thus giving it a edge over a overclocked 560ti.
 
You must log in or register to reply here.
Back
Top