My Asus DC II GTX 680 mini review and voltage mod

[chimaxi83]

Hey guys, thought I'd post info on what I did with this voltage mod, just in case anyone else has this card and is looking to push it a bit. Some of the guys at Kingpincooling forum helped me out, and turns out this was a lot easier than I initially thought. This post will mainly be informational on the card and the mod, and I will add some before and after testing in the next day or two. I'll be posting this on a few forums that I'm a member of, in case you see this copy/pasted under this username or my other, xxmastermindxx.

A few words about the card. It is water cooled. I really didn't do much testing with air, because I was going to up voltage anyway and it's primary purpose was to be watercooled anyway. Also, I own the OC version, couldn't grab a TOP. Only difference is a healthy factory overclock. That being said, I flashed the card with a TOP BIOS, so please take this info and review as if it were the TOP version, as it is now identical to one for all intents and purposes. The biggest deal about this card, in my opinion (other than the triple slot cooler, of course), is it has what Asus calls "VGA Hotwire" built in, and this is what it is according to them: "VGA Hotwire allows you to plug and solder wires on the card’s voltage regulators and accurately read and control Vcore, Vmem, and PLL voltages on a hardware level."

More on this later. The card looks to be well built, definitely better than reference in my opinion. Bigger PCB than reference, 10 phase VRM for GPU power (compared to four on reference cards), easy voltage mod points, great cooler. Out of the box, voltage is locked like any other 680. The limit is 1.175V, however my multimeter actually shows it occasionally hitting 1.215V under load, which coincidentally is the old limit that EVGA Precision X had. This is prior to any modding. Software only shows it up to 1.175V though, even when I was feeding the card 1.35-1.4V. Anyway, the only thing that is really lacking, in my opinion, is inadequate VRM and VRAM cooling.

Now, some pictures. Sorry about the relatively poor quality, but I'm taking these with a camera phone. Need high res? Google reviews of this card.

Has this box ever lied? (replaced embedded pics with link due to 10 pic limit)

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Not going to lie, other than test fitting it in my case to get a general idea of playing well with my other card, the card did not stay in stock, air cooled condition for long lol. I didn't get a great idea of its air cooled performance other than a little bit of BF3, where it hovered in the mid 50C's at around 1300MHz. I put it under my existing Gigabyte reference but then switched it once I changed my loop around and put my block on it.

First fitting:

DC II on top with block installed:

Side note: Although this card is a triple slot, you can in fact fit two of them on most boards, in my opinion. I have a P8Z68-V, and the slots are spaced apart just right for triple slot cards. They will be tight if you leave the air coolers on, but it's doable. Here is a picture of the clearance from the cooler to the next card on the bottom, it is ~1/4":

The DC II cooler itself seems to have overlooked the fact that GK104 die is so small. Only 3 of the 5 heatpipes make contact with anything, making the other two heatpipes useless imo. They reused the same design, obviously (no big deal though):

Remember the VRAM/VRM cooling I mentioned? The VRM's have a small heatsink on them, but it is not connected to or directly cooled by the DC II cooler itself, other than the warm air being blown through the DC II heatsink. They get pretty warm at stock. As I write this post, they're at 53C at idle voltage on the outside of the heatsink, and the temp probe I installed directly on the chips shows around 62C. High, but definitely within specs, especially since it's a bank of 10 VRM phases dumping heat into a small heatsink. There is no built in VRM temperature monitoring that you can read with HWiNFO64, for example, like some cards have. Second point, the VRAM came with ZERO cooling on it, which was weird, because it also gets pretty warm under load. I installed my own copper sinks, and they get hot enough to hurt, along with the small VRM heatsink:

The card, like I said, is the OC version. However I flashed it with the TOP BIOS, so other than possibly higher overclocking ability due to possibly higher binning, the cards are equal. 1137MHz stock clock, 1202MHz boost clock. In use though, it actually boosts to 1280MHz, without touching any overclocking or voltage:

Sneak peek at 1.35 volts clock speed. An offset of +125 gets the max boost up to 1406MHz, and it stays pegged there in everything except 3DMark11 tests 1 and 2, where it fluctuates:

Now, onto some fun stuff :thumb:

 

[chimaxi83]

Now onto the voltage modding. First off, unless you have adequate cooling, you shouldn't bother. You can test your luck on air if you'd like, however I wouldn't recommend it, and I didn't bother to try. Moving on.

Here are the 6 voltage points. 3 points on the left are for reading voltage, the 3 points on the right are for adjusting voltage. You can read/adjust GPU voltage, VRAM voltage, and PLL voltage. To enable control through these points, you must also bridge the circled points.

To go above the reference maximum of 1.175V, you must also remove the resistor labeled PGR100 that is circled:

All I've done so far is a mod to GPU voltage. I plan on playing with RAM/PLL voltages soon, and will update here with any improvements when I do.

As far as the mod is concerned, the easiest of the easy is basically, if you own a Rampage IV Extreme motherboard (which Asus doesn't specifically tell you, they just mention a ROG board), you can solder wires included with the motherboard to 6 solder points on your DC II 680, connect them to the motherboard, and monitor/control your DC II voltage through what is basically the BIOS. Anyone with soldering skills can do it. If you're like me though, you don't want to HAVE to buy a $400+ motherboard and a SB-E CPU just to easily overclock your card. That is where this mod comes in, no ROG board needed :thumb: More power, more (possible) overclocking headroom.

What you will need:

1. First and foremost, adequate cooling. More on this later.
2. Second, the understanding that you are voiding your warranty and taking a risk with your shiny new $500+ dollar card, and if you blow it up, it's your fault
3. Asus DCII GTX680 (TOP or OC, doesn't make a difference)
4. Digital Multimeter
5. Means to monitor temperatures, you will need this for VRM especially
6. Soldering iron/solder/skill
7. 10K Ohm VR/pot/trimmer
8. Some wire
9. Electrical tape/liquid electrical tape/hot glue to insulate some connections

I installed a temperature probe between the VRM heatsink and the VRMs. The probe is connected to my fan controller. As far as accuracy, it is within 2C of my multimeter temperature probe, and my IR temperature gun. The card is not equipped with built in VRM temperature monitoring through software, so this was necessary. If you are leaving your VRM's air cooled, like I am (until full cover blocks are available, probably), you will NEED to monitor your VRM temps. I'm not sure what is safe, but I pull the plug at 90C. Luckily, I didn't come within 10 degrees of that. There is a pic of probe installed in first post.

I started by soldering a different color wire to each of the GPU mod/monitor points, as well as bridging the empty contact pads right below that I mentioned earlier:

You can think of each of those points as the positive polarity. Negative polarity will be ground. So the OVG point will be connected to one leg of your variable resistor, and the middle leg of the resistor will then go to ground to complete the circuit. For ground I used one of the pins on the PCI power connector, circled in red. This is important. Make sure that your variable resistor is at MAX resistance before you solder wires to it. You want it to read 10,000 ohms. This way, you are not mistakenly feeding the card extra voltage before you mean to. Also, make sure that you solder to the legs that you measured, if you're using the typical 3 leg trimmer. If you measure legs 1 and 2, solder to those two. If you mix them up and solder to legs 2 and 3, you will have the opposite amount of resistance, i.e. zero, and will probably instantly fry your card. Check, double check, and check once more. You've been warned. Mod circuit done:

The point labeled GPU, which is to measure voltage, can just go to the positive lead of your multimeter. The negative lead of your multimeter will go to ground, and for that I just shoved it into one of the PCI power connectors:

I wrapped the trimmer with electrical tape to insulate the two legs connected to the mod wires, as well as the empty third leg:

Now when you adjust the resistor, you won't see much change until you pass 5K, which means you'll have to make quite a few turns of the screw. The reason I didn't install a 5K to begin with is because if i did, I'd already be pushing 1.23-1.24V. Anyway, I saw 1.3V at close to 2K ohms resistance. Should be noted that once your resistance gets passed about 5K or so, voltage will start to rise much more quickly, so you need to turn the screw much more slowly. Also, don't measure resistance while your system is powered up. To accurately measure, it needs to be off, and one leg of the resistor needs to be removed from it's connection. I did my measurements once I set the voltage I wanted.

I went straight away to 1.35V to find the clock ceiling there. I did get a batch of stock TOP clock testing done, and will be comparing it to the highest overvolted overclocks I've achieved so far. I will say this, I don't think this card is an amazing overclocker, sadly. At 1.35V, 1406MHz seemed my stable limit, which wasn't much more than my stock voltage stable limit of 1331MHz. Overvolted and overclocked, max temps for the core rarely hit 40C. VRM temperatures were close to 70C on average.

I also upped voltage to 1.4V, and that found me stable at 1455MHz. I'm not sure it's worth it though, because let's face it, that voltage is dangerous. I'm ok with it for benching, but for gaming and 24/7 running, 1.3V will be my limit. At least until more people mod their cards and post their experience, and I get a full cover block. Core temps at 1.4V also rarely passed 40C, but VRM's approached 85-90C. Too close for comfort, in my opinion.

Anyway, here it is, unmodded voltage under load, showing beyond the max of 1.175V shown in software. I guess EVGA was onto something with the initial voltage limit in their software being 1.215V:

I can't stress this enough, you need adequate cooling for this. If you water cool, the core will be a piece of cake. VRM's, not so much. This is the VRM temperature under Battlefield 3 load at 1.3V and 1361MHz, with very light air from a case fan hitting the heatsink, similar to what the DC II cooler would provide (temperature on the right, the other temperature is ambient air inside case). If you plan to over volt, the VRM's definitely need adequate cooling:

Here is VRM temp with a regular house cooling fan blowing directly into the case, with same Battlefield 3 load. Much better, but inconvenient and loud:

Well, that's all the info I have on this for now. I'm curious about power consumption, as I've hit at max about 137% power usage. I'm sure this draws less power than, say, 470 SLI for example. Your voltage limit is probably going to have to be whatever you feel comfortable with, to be honest. One of the guys at Kingpincooling who normally does nothing but crazy mods and benching said 1.5-1.6V should be safe for Kepler... keyword should. My cap will most likely be 1.5V, I bought the card to push it. Not sure about that though. Any questions, please feel free to ask.

 

[chimaxi83]

Reserved for game performance and benchmarks. Will add these as I go along. If there are any requests, let me know.


3DM11 Extreme 4173

3DM11 Performance 12039

Vantage Performance 40968

 

[spinejam]

Nice work -- thanks for sharing!

 

[Don Karnage]

You crazy bastard

 

[chimaxi83]

You crazy bastard

Crazy would've been following that guide at Kingpincooling on my reference card. I'm glad I didn't heh. The pics make it look easy, but when you look at your card and see how freakin tiny those pins are, you :'( lol

 

[Don Karnage]

Crazy would've been following that guide at Kingpincooling on my reference card. I'm glad I didn't heh. The pics make it look easy, but when you look at your card and see how freakin tiny those pins are, you :'( lol

Hurry up and do a 3dmark11 run for me before i pass out

 

[chimaxi83]

Best runs so far. Boost pegged at 1430 MHz, VRAM at +400 (6800).

3DM11 Extreme 4173
3DM11 Performance 12039
Vantage Performance 40968

 

[Don Karnage]

Best runs so far. Boost pegged at 1430 MHz, VRAM at +400 (6800).

3DM11 Extreme 4173
3DM11 Performance 12039
Vantage Performance 40968

God damn bro that's very nice.

 

[Tempered81]

Nice work Chimaxi83. We enjoy seeing 1450mhz GTX680s. What are you expecting from pll overvoltage & vmem mod? I'm sure it will like some extra bandwidth for the scores

 

[Zanovar]

Very interesting read,cheers for posting that Chimaxi.

 

[Goatsecks]

I've got to admire your balls.

 

[d3fu5i0n]

Excellent work! :thumbsup:

 

[OILFIELDTRASH]

Nice. To squeeze that last little bit out of that card was expensive and time consuming. Personally I'd just called it good at 1300 on air. But that's what is cool about guys like yourself. You are willing to put the time and effort in and now you're sporting a beastly 1400mhz card running at 40c. Hats off.

 

[SlowSpyder]

1.45GHz 680... nice!

 

[Pray To Jesus]

NICE! Very good job.

 

[SirPauly]

What a nice read -- thank you!

 

[tviceman]

GOOOOODDDDD these need faster vram modules, your 1400mhz gtx680 is so bandwidth starved!!!!!

 

[cmdrdredd]

I must admit, while something like this is way beyond what I'd do and all it is pretty cool to see this info.

I'm also surprised that voltage doesn't kill these. Makes me wonder why it's locked down at all.

 

[OILFIELDTRASH]

I must admit, while something like this is way beyond what I'd do and all it is pretty cool to see this info.

I'm also surprised that voltage doesn't kill these. Makes me wonder why it's locked down at all.

$$$. Rma's have probably been cut in half as a result of a totally locked down card.

 

[tviceman]

I must admit, while something like this is way beyond what I'd do and all it is pretty cool to see this info.

I'm also surprised that voltage doesn't kill these. Makes me wonder why it's locked down at all.

I agree with this being pretty cool and also beyond what I'd do. I think a part of the voltage lockdown it has to do with the fact that they're bandwidth starved. I'm betting he's getting seriously diminished returns with anything past 1250mhz boost with 6800mhz vram. From Nvidia's point of view, why let regular consumers chance burning these up with big overclocks when returns are going to be strapped due to the memory bandwidth? Saves money on warranty work.

From everything I have seen, gtx680 needs 1:1 core/memory overclocks to keep scaling intact.

EDIT: Oilfieldtrash beat me to it.

 

[cmdrdredd]

You would think so, but really if the voltage doesn't kill the card at 1.4v you would think someone like EVGA would differentiate themselves by offering a card that goes up.

Maybe they know something we don't about running that voltage over time though.

 

[OILFIELDTRASH]

I agree with this being pretty cool and also beyond what I'd do. I think a part of the voltage lockdown it has to do with the fact that they're bandwidth starved. I'm betting he's getting seriously diminished returns with anything past 1250mhz boost with 6800mhz vram. From Nvidia's point of view, why let regular consumers chance burning these up with big overclocks when returns are going to be strapped due to the memory bandwidth? Saves money on warranty work.

From everything I have seen, gtx680 needs 1:1 core/memory overclocks to keep scaling intact.

EDIT: Oilfieldtrash beat me to it.

You know 1340-1400 might not even make a difference unless you can get past 7000mhz on the memory. I know I need 6800mhz for 1270 on the core.

 

[tviceman]

You know 1340-1400 might not even make a difference unless you can get past 7000mhz on the memory. I know I need 6800mhz for 1270 on the core.

Yeah it would probably only help in synthetic benchmarks. If Nvidia follows GK104 up with a GK114 next year or late this year, it definitely needs 7ghz vram modules. Even if their binning techniques only get 6600mhz due to memory bus limitations, at least some of the gk114-based cards would have more vram overclocking capabilities.

 

[guskline]

Chimaxi83, beautiful work. Obviously you are skilled in electronics.