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GTX 670 reference PCB - voltmod - Page 5

post #41 of 94

Sounds like your on the right track .. cant wait for some more results!

post #42 of 94
Thread Starter 
As I was modding with the current shunts, I screwed up with VFB-track. I had soldered a wire to VR to the VFB testpad... It was mechanically very weak. So when I laid the PCB on it's back, the wire cranked the VFB-testpad off along with the whole VFB track.. Then I fixed it biggrin.gif I took one string form a copper wire. I made it U-shape and soldered it in place.. It is so beautiful that I almost cried when I got it all soldered up. And it works =)

Also I put a resistor together with current limit feedback resistor. Took it of an old 6600gt.. It's a 10k resistor. The original was 22k.. This makes the current 3 times higher. It might still protect the circuit if a coil saturates..

Now I have +20% for power%.. I did 1.3V, 1372MHz test.. the power% rises to 103% and there is no throttling. I think the throttling might have also been OCP-based... It makes no sense that the card throttles at 105% when my power target is 112%..

I'll do more testing later this evening. Here's a picture after 3Dmark11.
https://www.dropbox.com/s/5u8aesysq0f0120/no_throttling.png

Also here is my current mark11 record: http://www.3dmark.com/3dm11/4863219 --> I clocked my CPU to the limit for this push..
Here is the 3dmark for this 1372MHz run: http://www.3dmark.com/3dm11/5102878 --> Graphics score is rising as it should.. To be continued =)
post #43 of 94
Have you considered competing on HWbot.org?
    
CPUMotherboardGraphicsRAM
E8400, E8600, 980BE T2RS+, P5E3, TA890FXE 8800GTS's,GTX's,GS,Ultra's,9600GT Lots of D9's and some crap DDR3 
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CPUMotherboardGraphicsRAM
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Hard DrivePowerCase
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post #44 of 94
Thread Starter 
No, I haven't. Do you think I should? Would I stand a chance? biggrin.gif
I do this for the fun of it, I'm not sure if I find the patience in myself to run multiple benchmarks..
I'm gonna run some tests now though, and update this post soon!

Raised core to 1399mhz, then heaven benchmark on. Screen went black, GPUv --> 0V.. OVP? Shouldn't be OCP because I set it so high....
Edited by Olper - 12/2/12 at 7:47am
post #45 of 94

Sick score for a Lynnfield! Your cooking with fire now Olper thumb.gif You may be right about the speed causing premature OCP issue.. speed will bring current increases quickly.. even with stock voltage. Cant wait to see you get this dialed in a bit more. You have a good shot at some nice bench scores in '01 and '03 .. and probably have enough CPU for '05 too.

 

 Good work! - Dont forget some pics of your completed mod - to post in the Vmod essentials thread wink.gif

post #46 of 94
Thread Starter 
Something is definitely throttling this card. GPU temperature is about 50C, so it's definitely not this. It's not Power% anymore - it measures about 85% (true value = 106%). Also it should not be OCP. The OCP limit is approximately three times higher than normally. For now it seems like 1398MHz is maximum for Heaven benchmark. Next step is 1411MHz. This will crash even if memory is not overclocked at all. I tried to increase voltage, but it just presented throttling to voltage and GPU frequency..I'll try 3dmark11 with 1398 next.

Palit model has only 4-phase buck. MSI has 5-phase and asus has 6-phase atleast on their direct-cu II top model. More phases is an advantage to inductor currents, mosfet currents, ripple voltages and ripple currents. Because this has only 4 phases and I'm driving this card above specification, I'm afraid the inductives saturate. When an inductive saturates, it's impedance collapses very suddenly, very low. It will cause a very large current spike. It can easily burn mosfets. I could fix this by raising the switching frequency. This would lower the max inductive current and at the same time lower ripple voltages and ripple currents... The downside is that it will increase switching losses of the mosfets. I should have a method for measuring mosfet temperatures before I do this mod. I think the fets will be quite cool because I have a full cover block.

Something to do for the next week =) I'll borrow some thermocouples and insert one between a fet and the GPU block. If the temps are low, I'll raise the switching frequency.

EDIT:
I ran 3dmark11: http://www.3dmark.com/3dm11/5105585?key=K8XViuJC8KINtLwiWT5MMw
CPU @ 4300MHz
GPU 1385MHZ(core) / 3703MHz(mem)
Edited by Olper - 12/2/12 at 9:03am
post #47 of 94
You can blame nvidia. They're adding all kinds of ocp protections to the 600 series GPU. Some of it is in their drivers to. Like for example, the 680's have a cold bug around -50C using a dvi port, but it moves to around -120C using a vga port. Funny stuff. Nvidia neutering ftl
    
CPUMotherboardGraphicsRAM
E8400, E8600, 980BE T2RS+, P5E3, TA890FXE 8800GTS's,GTX's,GS,Ultra's,9600GT Lots of D9's and some crap DDR3 
Hard DrivePowerCase
Seagate 250GB + 80GB WD for benching TT 875w, Corsair 650TX Custom bench station 
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CPUMotherboardGraphicsRAM
E8400, E8600, 980BE T2RS+, P5E3, TA890FXE 8800GTS's,GTX's,GS,Ultra's,9600GT Lots of D9's and some crap DDR3 
Hard DrivePowerCase
Seagate 250GB + 80GB WD for benching TT 875w, Corsair 650TX Custom bench station 
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post #48 of 94
Thread Starter 
Stupid Nvidia biggrin.gif
I hope I can fix these issues.. It would be nice to have the card fly over 1400mhz
By the way, I mod the OCP by lowering resistance between RC and ILIM. Maybe I should mod by pulling down IMON... It should not make a difference.. What do you guys think? Does it matter which one I change? Datasheet says that OCP is disabled by connecting ILIM directly to RC.
post #49 of 94

So long as they are connected on the PCB.. it should not matter ; and your mod should be sufficient. I think you on to something with the inductors and your increase to Sw. Freq. Can you measure voltage at the input and output sides of the inductors to check for droop please?

 

*Some GPU/IC need "total" OCP mod.. and "per phase" OCP mod .. like some Volterra IC. Maybe Richtek has some sort of total & per phase mod as well thinking.gif I havent bothered to pour into the DS much at all though Im afraid. 

post #50 of 94
Thread Starter 
Uhh, learning hurts. But then it's great to know things biggrin.gif Read some of the datasheet again...

I think IMON signals output current information as an analog signal. .datasheet: "IMON: 0 mV to 900 mV analog signal proportional to the output load current. VSN referenced". I think NCP5392 does not use this information at all, but it's there for other circuits to read. Now that I fiddled with ILIM, it means that the NCP5392's OCP limit is higher. Still it sends correct output current information forward. Maybe the GPU reads this signal and throttles at a limit. I'm gonna put a pulldown on this...
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