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Safe overclock limit for Sapphire 7950 Oc edition(Dual-X) & throttle issue with boost

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June 14, 2013 8:18:48 PM

Friends

Hi I am facing throttle issue with sapphire 7950

The card has core clock of 850 and boost clock of 925 and memory clock of 1250

voltage by default is 1.250. The clock jumps between 850 & 925 and this lead to boost or I call it throttle with frame rates creating high variance in frame rates.

Now I have OC with sapphire trixx to +15 power & core clock @ 1100 and memory @ 1500 which is giving better frames and slightly high temps like 65-74C while gaming. Need to know how much more it can be pushed if required or please share your experiences in Overclocking 7950.

Thanks


a c 103 K Overclocking
June 14, 2013 10:46:29 PM

Do you see these jumps when not overclocking and are they occuring at regular time intervals? Does your mem clock jump/dip/spike? My first instinct is thermal throttle kicking in at those temps
June 16, 2013 11:09:08 PM

Hi thanks for your revert I have observered memory clock to stay at 1250 when the core clock jumps between 850 to 925.
The temps are below 70 degree C.


Overclock Behavior:
Now I overclocked this card to 1120/1475 gradually when i run furmark the card GPU usage throttle from 100% to 64%, 3-4 times during 1 minute benchmark and temp goes upto 74 C .
No artifacts no freeze here but GPU does throttle 2-3 times Core clock as well as memory clock both come down to 850 and then goes back up.
IS it stable and can I go further.

Related resources
a c 103 K Overclocking
June 17, 2013 6:02:31 AM

This smells of thermal throttling more n more. Do you have custom fan curves set? Are fans running full tilt or ramping under load? If they are staying quiet constant speed from no load thru testing it makes the issue obvious based on what you've stated. Have you had the heatsink off recently or moved the card? Heatsink attached tightly? Mi ghost t even want to consider reapplying a quality thermal grease
June 17, 2013 8:20:08 AM

dear buzz yes I did custom fan profile set in trixx for overclock but other wise I keep it at automatic , fans reach 55% and temp reach 70C for benchmark on furmark else it stay low. I have not touched the card after I installed it. for BF3 the following results are there on all ultra and 1080p
fps min 53 max 131 avg 86 this for mission 1 after the train. achieved with 1120/1475 settings


ONLY issue I am facing is when running furmark card GPU usage show drops down is it normal how is the experience with furmark or suggest any benchmark I can run and share results with you . card is giving good performance just want to learn the overclocking stability bit.

thanks
June 17, 2013 7:25:06 PM

set the power limit to 20%, it may fix the problem.
a c 103 K Overclocking
June 18, 2013 2:16:40 PM

Wait a min here... originally you posted seeing clock fluctuations. But now you say it's usage fluctuations. These are 2 different things. Usage will flux based on system need. Clocking should not while on 100% loadbbenchmarking.
June 19, 2013 2:09:50 AM

tried power limit to 20% yes it helps in overclocking what is the max core clock and memory clock which is safe for 7950 OC edition
June 19, 2013 5:17:25 AM

kanuj5678 said:
tried power limit to 20% yes it helps in overclocking what is the max core clock and memory clock which is safe for 7950 OC edition


OC your card until you see artifacts. Then lower the settings. Increase core clock gradually to find best stable point.
June 19, 2013 10:33:47 PM

@ spike which tests should I run for stability testing I already used Furmark, is unigine valley benchmark any good???

@ Buzz to clarify - clock fluctuation was happening due to low tdp when i increased the power to +20% it gets stopped and maintain clock of 1100/1475

But GPU usage comes to 64% from 100% 4-5 times while running furmark , I think this is due to lack of voltage which causes the card to throttle as the temps are like 70C, with low clock like 1000 it doesnot throttle while running bench mark like furmark @ 1.1250 volt any thougths

I have been doing testing for games & benchmarks for 2-3 weeks with thorough analysis... seems like fun activity.
a c 103 K Overclocking
June 20, 2013 12:55:43 AM

Increasing the clock will cause reduced occasional need to usage due to faster processing and bus - that said, it still smells of thermal throttle - id remove current cooler, re apply a decent TIM, either try n re use or order new thermal tape for mosfets as TIM isn't usually thick enough to contact those. Make sure your fan curves are set to max for all temp limits - just run em full blast 100% of the time - and re run tests. Keep in mind, TIM re seat requires a bit of burn in, so run a few good hot/ cool cycles. Furmark, Uniengine Heaven, and OCCT are my faves for benching
June 20, 2013 2:25:47 AM

kanuj5678 said:
@ spike which tests should I run for stability testing I already used Furmark, is unigine valley benchmark any good???

@ Buzz to clarify - clock fluctuation was happening due to low tdp when i increased the power to +20% it gets stopped and maintain clock of 1100/1475

But GPU usage comes to 64% from 100% 4-5 times while running furmark , I think this is due to lack of voltage which causes the card to throttle as the temps are like 70C, with low clock like 1000 it doesnot throttle while running bench mark like furmark @ 1.1250 volt any thougths

I have been doing testing for games & benchmarks for 2-3 weeks with thorough analysis... seems like fun activity.


I personally use: Furmark, 3DMArk Vantage, 3DMark 11, Call Of Prypiat benchmark tool and sometimes MSI Kombustor. Use Unigine Heaven Benchmark.
June 20, 2013 4:51:57 AM

@ buzz thanks for input mate any guide to do it as i have not touched the hardware ever for 7950 and which thermal paste to apply

@ spike thanks I will run 3d mark 11 and vantage and share results at different speeds so we can have further insights

!