I've reached +125 MHz and +495MHz with my SC ACX 2.0, and made it through 3DMark Firestrike two times and Heaven 4.0, Valmey 1.0 and 30 min FurMark BUT.
I cant pass with 125/250MHz in 3DMark. And sometimes, my latest stable clocks doesnt always work either. Got any ideas?
Powerlimit at 110 and voltage at +37.

PanicAttack96
I've reached +125 MHz and +495MHz with my SC ACX 2.0, and made it through 3DMark Firestrike two times and Heaven 4.0, Valmey 1.0 and 30 min FurMark BUT.
I cant pass with 125/250MHz in 3DMark. And sometimes, my latest stable clocks doesnt always work either. Got any ideas?
Powerlimit at 110 and voltage at +37.

 
you post is not helpful
 
The +'s you posted do not tell us what the Core and memory clocks run at with the setting you posted therefore we have no idea if its a good clock or not. also no ifo on temps and fan profile
 
for example My 970 FTW+ is running at a core of + 129 and memory @ stock (as I mainly fold and the  memory setting is overwritten by the bios when using Cuda on these cards)
The fan runs @ 66% and the temp is around 50c
so the core is running @ 1546 not to shabby for an FTW +
 
You also need to understand that the Core should be clocked first as its the most important and the memory much less so, but that the memory overclock may push you past the Power threshold
 
Try returning the memory to stock and leave the Core @ +125 is the card then stable when running the benchmarks? - if so then put +100 on the memory and retest, if its stable then add +50 to the memory and yes you got it retest again, as soon as you find an unstable test, drop it down 50 and leave it there  :)
 
running it at the highest power and voltage limit is also not always the best result, I hope you have set a decent fan profile to keep the card below 75C at all times - it will start to downclock @ 79C so you need to keep as far away from that as possible
 
 

the + xxx on the core will have nothing to do with final core clock.   different cards will run at different clocks with the same offset

EVGA GTX 970 FTW+...  Out of the box, the core ran 1417 MHz under load, even though it was rated to run at 1367 MHz.  I've got it running at 1540 MHz stable.  Memory was at 7010 Mhz.  It's stable at 7800 MHz.  I opened the voltage up, but it never exceeds 1.240 V - stock is 1.200 V.  I've run several benchmarks - Metro Last Light, Tomb Raider, Unigine Valley, etc.  I'm seeing a 10% frame rate improvement across the board.  The core temperature never exceeds 76°C.

garik
You guys are nuts to OC a GPU card, In my opinion its the worst thing you can do to a computer component. Just my opinion is all  :)

I purchased an EVGA 680 the day they launched and had to spam the site for hours to get one.  I spent a few days tinkering and settled on an 11% OC.  I ran with that core and memory overclock for roughly 5 years straight without a single issue, and heavy gaming until I just purchased a 980 yesterday.  Why not have more fps if you can?

garik
You guys are nuts to OC a GPU card, In my opinion its the worst thing you can do to a computer component. Just my opinion is all  :)

On what scientific evidence do you base your opinion?  According to EVGA - and I agree with them - speed does not damage electronic components - heat does.  As long as heat is kept under control, overclocking a CPU or GPU will not shorten its life appreciatively.  I have a six year old i7-875k with a massive Noctua cooler installed.  Stock for that CPU is 3.2 GHz.  It's been running at 3.8 for six years.