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Prime95 Blend Stability Issues?

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Leegit

Member
Joined
Apr 4, 2013
Location
Kansas
Trying to test for stability on my new 6700k and it keeps crash at ~1 hour. Even at stock settings? Is there a particular version I should be using? I have the newest one atm. :confused:
 

EarthDog

Gulper Nozzle Co-Owner
Joined
Dec 15, 2008
Location
Buckeyes!
HOw does it 'crash'? Not rounding errors? Freeze? What remdied have you tried? Are you overclocked? IF so, roll back to stock...

More (some..) information please! :)
 
OP
Leegit

Leegit

Member
Joined
Apr 4, 2013
Location
Kansas
Most the time I get an 1 error on a thread then it says it crashed. Few times just crash straight up. I already rolled back to stock and tried it again. Same result. I'm thinking maybe its my memory, I'm gonna switch out for my 2x4GB 2400 HyperX kit and try again.
 

EarthDog

Gulper Nozzle Co-Owner
Joined
Dec 15, 2008
Location
Buckeyes!
Is this the rig in your signature? Is that 4x4GB I assume?
What temps are you hitting?
Does it happen in Small FFT?
Blend does test more memory and IMC than Small FFT. Run small FFT and see if it trips up at the same time with your existing memory.
 
OP
Leegit

Leegit

Member
Joined
Apr 4, 2013
Location
Kansas
Sig is my old rig, haven't updated it yet. I have 6700K + EVGA Z170 Stinger + Kraken x61 push/pull + 2x4GB DDR4 2400 HyperX or 2x8GB DDR4 3200 Corsair Vengeance... I was doing 4.5 GHz on 1.25-1.29V+ (temps pushing 75-80C). I need more volts and cooling I think... and it would get to about an hour and fail. I'll try just Small FFT for an hour and see what happens. Thanks :thup:
 
Last edited:

EarthDog

Gulper Nozzle Co-Owner
Joined
Dec 15, 2008
Location
Buckeyes!
Update your sig. ;)

You may need to add a small touch of SA voltage (try .05 to .1)... but you shouldn't really with 2x8GB ddr4 3200 MHz...
 

EarthDog

Gulper Nozzle Co-Owner
Joined
Dec 15, 2008
Location
Buckeyes!
Right... its just hard to search/find a specific file. 99.99999999999999% say the program, not the filename. :)
 
OP
Leegit

Leegit

Member
Joined
Apr 4, 2013
Location
Kansas
I saw something in the forums about Prime95 ver 26.6 (should I use this one?) being the one before they started doing the AVX commands and them being more strenuous but not realistic.... just for gaming? What about programming? Sometimes I'm working with large data sets and need full CPU power over a extended time frame? Should I be pushing my CPU benches this hard to be more accurate on stable overclocks?
 

wingman99

Member
Joined
Dec 10, 2003
I would test thoroughly with Prime95 for reliability for your large data sets. You should use the newest prime95 in case your programs use AVX, also use the option of round off checking, it test the floating point of the CPU. I passed prime95 for 15 hours:).
 
OP
Leegit

Leegit

Member
Joined
Apr 4, 2013
Location
Kansas
I was on vacation the last week :)

So before I left I rolled back to stock settings and lowered my memory to 2133 from 3200 MHz (XMP). I was able to pass Prime 95 Small FFTs / Blend over multiple hours. Since then I have up'd my CPU to 4200 MHz and it passes Prime 95 Small FFT with as little as 1.10V over 6 hours. If I drop to 1.075 V it will crash (worker errors / BSOD). After that I went to Prime 95 Large FFTs and so far it takes at least 1.20V for it to pass 3 hours, but it still ended up producing errors and the workers stop...

Back to my original question... I am not doing any programming with AVX commands but I do want to have an idea of when I am truly stable. Should I move to a different version of Prime 95 (pre-AVX) ? Or use a different stress test entirely? Keep in mind I do not have a GPU yet, as I am waiting to purchase the 1070. I'd like to characterize my 6700k before I add the GPU.
 

Kenrou

Member
Joined
Aug 14, 2014
If you're doing only gaming/web browsing/light tasks 26.6 will suffice, but if you do image or video coding, or anything with AVX on it, you need 28.9. Ex: my rig does 4.7ghz 1.33v for day to day gaming/browsing, no errors, no crashes, passes 26.6 24h. 28.9 needs 1.39v to stay stable at the same speed just because of AVX, i do video encoding so i keep 2 profiles in BIOS and switch as needed.

There's much argument and drama over it, in the end its really up to you and what you use your PC for :shrug:
 

wingman99

Member
Joined
Dec 10, 2003
I do heavy web browsing with a lot of tabs also gaming and a lot of other things, if your PC hardware is not 100% stable your looking for trouble corrupted data to the storage drive or a crash of your web browser or games and other things. When you run prime95 it will also test the floating point of the CPU that is where the math is done and I don't like my PC not to calculate correctly. The new 28.9 prime95 also tests the AVX instruction set which is part of the floating point. A CPU is pure math calculations all you need when you overclock the core is pure math stress program and Prime95 can test and stress all the transistors in the CPU at the same time.

I also use round off checking in prime95 because a CPU rounds numbers, My i5 6600k failed round off checking when overclocked to 4.5GHz with a voltage of 1.29v increased to a safe margin of 1.31v passed 15 hours of prime stable.

You just have to remember that intel makes the CPU 100% stable in calculations otherwise we would have all kinds of trouble with rounding and binary flipped numbers, some programs can take the error like Encoding and calculations, games etcetera.

The reason why prime95 is the most stressful it is pure math and does not need much overhead of software language in memory to convert it so it is in and out of the CPU fast and smooth=full load.
 
OP
Leegit

Leegit

Member
Joined
Apr 4, 2013
Location
Kansas
How do I toggle the floating point and rounding checks when I use Prime95 ? :shrug: My work is mostly regarding computational physics so I use that a lot.
 

wingman99

Member
Joined
Dec 10, 2003
Hi, go to Advance on the top left of the window check the box (round off checking) round off checking is floating point. For math you defiantly want a %100 stable CPU, when you overclock you have to watch out for bit flip and the prime95 will defiantly test for that. One other thing I did not mention much is that a unstable CPU will eventually corrupt something on the storage drive and you wont no what is causing the trouble, it's just one of those things if you can't decompile or run a debugger on the OS or program you will have to reinstall.
 

Kenrou

Member
Joined
Aug 14, 2014
I do heavy web browsing with a lot of tabs also gaming and a lot of other things, if your PC hardware is not 100% stable your looking for trouble corrupted data to the storage drive or a crash of your web browser or games and other things. When you run prime95 it will also test the floating point of the CPU that is where the math is done and I don't like my PC not to calculate correctly. The new 28.9 prime95 also tests the AVX instruction set which is part of the floating point. A CPU is pure math calculations all you need when you overclock the core is pure math stress program and Prime95 can test and stress all the transistors in the CPU at the same time.

You're missing the point, if you pass 24h 26.6 (yes with floating point and rounding checks) you're for all intents and purposes 100% stable for anything except AVX. So if you only game and browse you will do it at the same settings with less voltage and therefore less heat. Whats the point of making the cooler/case fans work harder ?

If you're doing important work then yes i completely agree that you should use 28.9 with all the bells and whistles turned on. Just don't panic when you see the temperature shoot up ;)