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Discussion Starter · #1 ·
Hey guys - I followed all the guides on here, flashed Skyn3t's 3A bios on my 780 and have been able to successfully up the voltage to 1.325 and beyond. I have been testing the max clocks I can get without artifacts at the lowest voltage, and ran across a strange circumstance. Using Heaven benchmark, I got my clocks up to 1372 core / 7000 memory stable at 1.325v, and that's a repeatable result.

When I run 3dMark, I can get to 1293 core at 1212v or anything above that, with PT (power slider) at 100.

But if I exceed that number by another 25, I get a hard shutdown of my PC as soon as the first test is done loading. I can throw voltage at it (have gone as high as 1.425 (+0.025) for 1.450 with no success. I have backed my memory back to 6000 while doing the above. I have pushed the PT to 150% with no success. I'm at a loss. It's almost as though it sees 1300+ and won't let it run.

Again, I can push the clocks to 1372 @ 1.325 in Heaven / BF4 / Valley, etc., no issues. At these clocks and power I'm getting GPU temps of about 36 C sustained. No artifacts or anything.

I don't feel its a power supply issue. I have a 1000W Rosewill semi-modular PS with 100A no the 12v rails (although it is not single rail) and I have run a 780 ti on this same build and also run 2 780's in SLI on this build (same card in fact as primary) without issues.

Other than backing out my modest 4.5GHz CPU OC (just got the CPU haven't messed with it much yet or BIOS settings) and trying it, I am at a loss.

Any ideas / thoughts / that might get 3dMark to play nice so I can see what kind of score I can achieve?

Thanks!
 

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Quote:
Originally Posted by gqneon View Post

Hey guys - I followed all the guides on here, flashed Skyn3t's 3A bios on my 780 and have been able to successfully up the voltage to 1.325 and beyond. I have been testing the max clocks I can get without artifacts at the lowest voltage, and ran across a strange circumstance. Using Heaven benchmark, I got my clocks up to 1372 core / 7000 memory stable at 1.325v, and that's a repeatable result.

When I run 3dMark, I can get to 1293 core at 1212v or anything above that, with PT (power slider) at 100.

But if I exceed that number by another 25, I get a hard shutdown of my PC as soon as the first test is done loading. I can throw voltage at it (have gone as high as 1.425 (+0.025) for 1.450 with no success. I have backed my memory back to 6000 while doing the above. I have pushed the PT to 150% with no success. I'm at a loss. It's almost as though it sees 1300+ and won't let it run.

Again, I can push the clocks to 1372 @ 1.325 in Heaven / BF4 / Valley, etc., no issues. At these clocks and power I'm getting GPU temps of about 36 C sustained. No artifacts or anything.

I don't feel its a power supply issue. I have a 1000W Rosewill semi-modular PS with 100A no the 12v rails (although it is not single rail) and I have run a 780 ti on this same build and also run 2 780's in SLI on this build (same card in fact as primary) without issues.

Other than backing out my modest 4.5GHz CPU OC (just got the CPU haven't messed with it much yet or BIOS settings) and trying it, I am at a loss.

Any ideas / thoughts / that might get 3dMark to play nice so I can see what kind of score I can achieve?

Thanks!
It doesn't have a +12V capacity of 100A because amperage is multiplied by the voltage that you're using. In this case, 12V. So, 100 x 12 would be 1200W. What's the exact make and model of this Rosewill PSU?

To get to the question at hand: you're probably just finding the limit of this video card. :/
 

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Quote:
Originally Posted by gqneon View Post



I was incorrect. It is a 1000 watt unit but only has 52A continuous. I'm wondering if this could be a problem with one gpu and one CPU in this build.
You're probably tripping an OCP on one of the rails. Plug in the extra PCI-E connectors and use those (one from each rail) on the 780.
 

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Originally Posted by gqneon View Post



I was incorrect. It is a 1000 watt unit but only has 52A continuous. I'm wondering if this could be a problem with one gpu and one CPU in this build.
That label must be extremely wrong. 52A is 624W which would mean that this is just a really crappy 650W PSU at best. 900W is 75A.

Even with 624W though, it should still be way more than enough for one video card - but if this unit is really that crappy that it's a 1000W PSU with a +12V capacity of only 624W (52A), then yeah, I would then be saying that this PSU is the culprit. However, I think it's just mislabled and it should really be reading 75A. Again though, if it's really 52A like it says, then wow... That would be one hell of a crappy PSU.

Personally, I don't know anything about this PSU (but that's not saying much), so I most likely wouldn't overclock with it until I learned more about it somehow.
 

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Discussion Starter · #6 ·
Ok so this PSU came with a main harness bundle that has a PCIE 6 and 6+2, which I was using on the lone 780. It has two more plug ins for 2 more sets of PCIE pairs, totaling 3 PCIE sets. So I took a 6 pin from one side and an 8 pin from another, hoping I was spreading the load. No more tripped power. I got into the low 1400's on core clocks and I'm convinced that this chip isn't going much further. I'm still pretty pleased overall though. I'm beating mild OC 780ti clocks (I had one and did my own testing for comparison) and since I got this 780 from a guy at a Pizza hut for $400, I'm not arguing that it's a pretty good deal for what it is.

That suggestion got me from the high 1200's into the low 1400's, so good call!

For being a reference card, I'd say pulling into the 1400's reliably is good enough.

Thanks for all the help!

Chap
 

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Discussion Starter · #7 ·
As an update, I found a photgraph on the Rosewill site of this power supply with a label that's identical except that in the total combined power column it says 75A not 52A, which would be more consistent with what everyone's talking about. It's a little shady no one in QC would have caught that and there are others that have seen the same thing that I was able to find online.

I read a HardOCP review of it's original Tuniq 1000W branding and it was mostly within spec, but I wonder if maybe my unit has more variance than their test sample and whether the aging of the capacitors on this (particularly the secondaries) might be occurring. I shouldn't have to split the load with a single GPU, but I understand the math of why that seemed to solve my issue.

Moving onto an SLI setup I think this would be a good PSU to shelf as a back up and move onto a more efficient and well known branded model.

I was thinking Corsair RM850 (slightly exceeds - by about 100-120W - what my rig should produce, overclocked, at 100% load and 100% duty cycle for benching, and knowing that this load would be less than likely to occur very frequently) or an RM1000 to give myself some extra amperage and breathing room with the same build.

I've read people with builds like mine seem to have no issue at all with a quality 850 PSU. And the tests for this unit and its AX860 brethren seem to be almost identical on the test bench, except that the RM is quieter by a LOT.

You guys have a lot of good knowledge, what would you recommend, even if its not what I am thinking?

Chap
 

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Quote:
Originally Posted by gqneon View Post

As an update, I found a photgraph on the Rosewill site of this power supply with a label that's identical except that in the total combined power column it says 75A not 52A, which would be more consistent with what everyone's talking about. It's a little shady no one in QC would have caught that and there are others that have seen the same thing that I was able to find online.

I read a HardOCP review of it's original Tuniq 1000W branding and it was mostly within spec, but I wonder if maybe my unit has more variance than their test sample and whether the aging of the capacitors on this (particularly the secondaries) might be occurring. I shouldn't have to split the load with a single GPU, but I understand the math of why that seemed to solve my issue.

Moving onto an SLI setup I think this would be a good PSU to shelf as a back up and move onto a more efficient and well known branded model.

I was thinking Corsair RM850 (slightly exceeds - by about 100-120W - what my rig should produce, overclocked, at 100% load and 100% duty cycle for benching, and knowing that this load would be less than likely to occur very frequently) or an RM1000 to give myself some extra amperage and breathing room with the same build.

I've read people with builds like mine seem to have no issue at all with a quality 850 PSU. And the tests for this unit and its AX860 brethren seem to be almost identical on the test bench, except that the RM is quieter by a LOT.

You guys have a lot of good knowledge, what would you recommend, even if its not what I am thinking?

Chap

RM series has a few cheap components and is generally not recommended since you can find higher quality units for about the same money or less.

Choose one from here if you must get a new unit but I don't see a reason to replace your existing PSU:
http://www.overclock.net/t/183810/faq-recommended-power-supplies/0_20
 

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Discussion Starter · #9 ·
**I guess my sig upload didn't take. My system is:

i7 4770k @ 4.5 / 1.35v
Asus Maximus Hero MB
2x4GB Patriot DDR3 2400 / CL9-10-10-30 @ 1.65v
EVGA GTX780 SC - Skyn3t bios V3A - 1411 core / 7400 mem @36C
Samsung 840 EVO SSD 750GB
Asus 1440p monitor
 

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With one GTX 780, even overclocked and overvolted that high, all you need is a good quality-made 650W PSU.
 

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Originally Posted by TwoCables View Post

With one GTX 780, even overclocked and overvolted that high, all you need is a good quality-made 650W PSU.
1.4V GK110 can use up more than 600W.

If you couple that high overvolt 780 with a properly OC'd LGA1155/1150 let alone LGA2011 CPU a 650W PSU wont be enough.

Fact of the matter is that extreme OCers have commented that each GK110 needs a 1.2kW PSU driving it if you want to reach the card's max potential. Now obviously air/water users aren't going to need that much juice but with relatively bad cold bugs on GK110, the differences aren't that big between water/LN2 usage. I've personally seen well over 600W for the card alone when going over 1.4V. Now if you star getting closer to 1.5V that number should quickly reach 700W range.

It's like in the GTX 580 days when extreme guys were seeing over 800W power use per card. However this time it's worse. GK110 is pretty tame with the stock power and voltage limits but once you get rid of those it's a completely different beast. 650W is fine if you don't plan on overvolting. If you do, it's hopelessly under the needed spec.
 

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Discussion Starter · #12 ·
Wow thanks for the fast replies. I wouldn't be considering replacing my PSU with my build if it hadn't given me some moment of pause with the power protection circuits hard powering the PC off with one GPU under full stress. Spreading the load from Rail 3 where my 2 PCIE plugs were routed from to 1 on 3 / 1 on 4 stabilized it, but I'm about to drop another GPU in here and will have to use both plugs on the 3/4 rails, or rob from the 12v rail on the main harness pair on 1 and 2.

It's worth noting that I had 2 780's in here with this PSU, not overclocked or volt modded, and it didn't appear to have any issue at all running basic benchmarks. But I originally had my PC @ 4.6GHz and when I put in the second card it started giving me BSOD until I backed it down to 4.5 @ the same voltage.

I'm just not real sure about the true output of this particular unit and I was thinking that the single rail would be the better way to go so I wouldn't be guessing which rail might or might not be over burdened until I find out with a hard power down or worse.

That being said, I don't mind having $200 in my pocket, either, so if its not needed - cool.
 

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Discussion Starter · #13 ·
So... A couple of changes since the last post. I went from 2 780's to 2 780 ti 's in SLI. I also switched to a. CM V1000 PSU and its not only quieter but it also has a very clean high amperage single rail, so I don't have to guess on if it can handle the draw or not. I have them both under water and flashed the VGA bios on both, but it seems 1.212 v is as high as they can go right now until someone works out how to get above that for the TI's. That said, my little kill a watt on this build shows a peak draw from the wall of about 680w and +/- 6A. Max on the old lower rated PSU with this build was 790... So there's definitely an improvement in efficiency with the new PSU.

I also delidded my 4770k and used some liquidcool laboratory pro metal TIM (first time working with metal TIM) and it dropped my CPU core @4.5 down to 23 idle 45 prime. So I've got all this head room just waiting for a vcore unlock for the ti's then I'm gonna make my power company love me.

Good times.
 
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