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Discussion Starter · #1 ·
So I'm trying to overclock my 875k, and it was doing fine at 1.34750 volts, pulling in about 47 stable GFlops. Bam BSOD. I figure it's a voltage problem so I go to the BIOS and kick up the vcore one notch up to 1.35000. I run Linx again but the time increased by a considerable bit, and the GFlops decreased to 37. I changed nothing except the vCore, and not even by much and I get less GFlops. Why?
 

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Was the 47 gflops consistent over multiple runs? Also background processes that seem to only use a tiny bit of cpu power can have a big impact on gflops.
 

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Discussion Starter · #3 ·
No my GFlops seem to change every time I run tests. And no, no background processes were in use, all testing conducted at the same time with no applications at all except Linx and RealTemp
 

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In my experience, longer times and lower Gflops indicate either an inefficient or unstable OC.

Have you had a fiddle with the CPU and North Bridge Skews in BIOS?

try this;

CPU Clock Skew..........................[50ps]
MCH Clock Skew..........................[100ps]

Actually, can you post your M.I.T. and we will have a look at all your volts.
 

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Quote:
Originally Posted by Sethy666;12050388
In my experience, longer times and lower Gflops indicate either an inefficient or unstable OC.

Have you had a fiddle with the CPU and North Bridge Skews in BIOS?

try this;

CPU Clock Skew..........................[50ps]
MCH Clock Skew..........................[100ps]

Actually, can you post your M.I.T. and we will have a look at all your volts.
I agree to this, typically a vast change in GFlops does indicate instability in a CPU. If it were 1-3 variance I'd say something in the background is requesting cycles.
 

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Quote:
Originally Posted by turtleslikejohn;12049104
So I'm trying to overclock my 875k, and it was doing fine at 1.34750 volts, pulling in about 47 stable GFlops. Bam BSOD. I figure it's a voltage problem so I go to the BIOS and kick up the vcore one notch up to 1.35000. I run Linx again but the time increased by a considerable bit, and the GFlops decreased to 37. I changed nothing except the vCore, and not even by much and I get less GFlops. Why?
Your overclock is unstable. A good overclock with nothing interfering with IBT or Linx will maintain consistant gigaflops within one flop from minimum to maximum.
 

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Quote:
Originally Posted by Poisoner;12050454
Your overclock is unstable. A good overclock with nothing interfering with IBT or Linx will maintain consistant gigaflops within one flop from minimum to maximum.
I agree with this. I've noticed unstable OCs producing some odd numbers for Gflops, both faster and slower than expected.
 

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yep unstable, my i5 would go from 55/56 one test then - 47 the next. Running 4GHz ofc. setting the vcore to 1.39v sorted it out completely. Mind you im only running 1.21 vtt, which needs higher vcore. Im still undecided if its long term safe to use 1.3 vtt to enable lower vcore, but its running well with good temps so I havent really gave it a second thought. Im upgrading to a p55 ud6 in a few days to allow better space between my gpus for a mental oc (24/7 900mhz) as the top one getts to hot atm with my p55m ud4. Ill be experimenting a little more to get a better idea of how to keep the gflops consistent but one thing is for sure, its a sign of instability.
 

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No higher vcore is needed to stabalise higher speeds, its impossible that more voltage will make a chip slower. On the other hand higher temps might bring instability which results in lower gflops, and those higher temps may be caused by higher vcore, if cooling is inadequate. I hit 77C tops, after 20 runs intel burn test, using 1.39vcore and 1.21. Vtt. Everything else auto. Bclk 190 x 21 via turbo enabled. Turning c states of stops it from going higher than 21 on an i5.
 
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