Topic Title: Bad Cores on 8350?
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Created On: 01/20/2014 03:55 PM
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 01/20/2014 03:55 PM
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camaroguy1998
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I have an 8350 on an ASUS M5A99FX Pro 2.0. The install went great and after setup and installing all drivers, I ran Prime95 just to test system and it blue screened almost immediately. I rebooted and ran Prime 95 again. In less than 1 minute the number 8 core errored and shut down. It gave a "Rounding gave a 0.5 expected less than 0.4" Then at about 5 minutes the number 5 core errored and shut down also. It gave an error of "Final result was 6F0FB5E4 expected 38100A5F" Prime kept running on the other 6 cores, I stopped Prime95 at 2 hrs. 15mins. With 0 errors and 0 warnings on the remaining 6 cores. Is there anything that can be done to help the bad cores or is this a RMA situation?

 01/20/2014 05:06 PM
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AMDforMe
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The cores are NOT bad. The mobo settings are less than perfect to run all 8-cores successfully under the P95 stress test. All cores are not exactly the same so a couple might need some fine tuning to run P95 without issue. A couple weaker cores are common. Minor BIOS tweaks will usually fix the issue if you have:

1. An FX-8000 series CPU approved mobo

2. Proper cooling of your CPU (core temp below 61C under load) - VERY IMPORATNT

3. A PSU and mobo design that can supply the power required

4. Your RAM passes an overnight test of Memtest86+ V4.20 or V5

Your Asus mobo should support the FX-8350 and as long as the other items are good, I'd spend a little time working the BIOS settings.

Often the power saving features can cause issues during P95 stress testing which is extremely tough for an 8-core CPU. The easiest way to check these is to disable Cool & Quiet, C6 mode, CPU thermal throttle, Turbo core tech, Application Power Management and C1E. Asus may use slightly different names but these are the key power saving controls.

If P95 runs OK with these disabled then you can step by step turn one item on until you find the issue. I've also found that raising the RAM voltage by .05v helps stability with 8-core FX processors. There are a list of other BIOS changes that can be made if you desire to run in manual mode but you might want to try the above suggestions first.



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Technical ignorance is NOT a destiny it is a choice. Do your homework so that you can make technically informed decisions and not be duped by advertising hype or mis-information stated as fact when its not.


 

 01/20/2014 06:08 PM
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camaroguy1998
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Originally posted by: AMDforMe The cores are NOT bad. The mobo settings are less than perfect to run all 8-cores successfully under the P95 stress test. All cores are not exactly the same so a couple might need some fine tuning to run P95 without issue. A couple weaker cores are common. Minor BIOS tweaks will usually fix the issue if you have:

 

1. An FX-8000 series CPU approved mobo

 

2. Proper cooling of your CPU (core temp below 61C under load) - VERY IMPORATNT

 

3. A PSU and mobo design that can supply the power required

 

4. Your RAM passes an overnight test of Memtest86+ V4.20 or V5

 

Your Asus mobo should support the FX-8350 and as long as the other items are good, I'd spend a little time working the BIOS settings.

 

Often the power saving features can cause issues during P95 stress testing which is extremely tough for an 8-core CPU. The easiest way to check these is to disable Cool & Quiet, C6 mode, CPU thermal throttle, Turbo core tech, Application Power Management and C1E. Asus may use slightly different names but these are the key power saving controls.

 

If P95 runs OK with these disabled then you can step by step turn one item on until you find the issue. I've also found that raising the RAM voltage by .05v helps stability with 8-core FX processors. There are a list of other BIOS changes that can be made if you desire to run in manual mode but you might want to try the above suggestions first.

 

As you noted the Mobo is 8000 ready.  I have a Corsair HX750 PSU, I would hope that would be plenty to run my setup. The memory is 16GB of GSkill RipJaw FS-12800CL9D(4x4) This memory was in my previous computer and ran flawlessly! Yes memtest ran overnite previously! My video card is an EVGA 560Ti SC which was also in my last computer with no issues at all.

I will disable all the items you listed and see what happens! Thank You for your help, its greatly appreciated!

BTW... I ran Prime95 again and #8 shut down in less than 15 secs. #5 shutdown in about 7mins. and now #6 shutdown after 15 mins. So its up to 3 cores giving errors.

 01/20/2014 07:37 PM
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QB the Slayer
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If the CPU-NB is not properly configured it can cause Prime to crash this way as well

 

QB



-------------------------

The MONSTER HTPC:

CPU: AMD FX-8350.||.Cooler: Corsair H80i
MB: Gigabyte 990FXA-UD7.||.RAM: 8 GB Mushkin Blackline DDR3 2000MHz (7-10-8-27-1T)
Case: CoolerMaster HAF 932.||.PSU: Corsair HX750
GPU:Asus R9 270X DirectCU II TOP.||.Audio: Creative X-Fi Titanium Fatal1ty Pro w/ Logitech Z-5300e (5.1, 280W-RMS)
System Drive: 2xSamsung 840 Pro 128GB RAID0.||.Working Drive: 2xMushkin Chronos 60GB RAID0

 01/21/2014 12:50 AM
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camaroguy1998
Peon

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Originally posted by: QB the Slayer If the CPU-NB is not properly configured it can cause Prime to crash this way as well

 

 

 

QB

 

Any suggestions on CPU-NB settings?

I tried disableing power management with very limited results.

Basically it ran Prime95 for 20 mins before any cores errored and shut down.

 01/21/2014 02:17 AM
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VWM
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Are you already installed the windows hotfix for Fx 8350?

Install this one first - Windows6.1-KB2645594-x64 - Then restart.

http://support.microsoft.com/kb/2645594   

Install this one after restart - Windows6.1-KB2646060-v3-x64

http://support.microsoft.com/kb/2646060

 



-------------------------

CPU: AMD FX-8350 (black edition FD8350FRHKBOOX) + Cooler Master Hyper 212 X Army (push/pull config. fans Enermax T.B.Silence UCTB12P) / MOBO: Asus M5A99FX Pro2.0 / GPU: Gigabyte Amd Radeon R9 279x ( GV-R927XOC-2GD ) / RAM: Kingston HyperX 2x4GB DDR3 1600Mhz / SSD: Samsung Evo 840 250Gb / Case: Coolermaster K280 / PSU: Chieftec Smart Series GPS-600A8

 01/21/2014 09:41 AM
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AMDforMe
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There are many BIOS settings that can cause the instability under P95 stress testing. It's worth noting that IME I have seen name brand DDR3 RAM go bad in as little as 2 weeks or even a few months. That's why I always test the RAM overnight with Memtest86+ when an issue develops.

I'd probably try manually setting the CPU vcore and also the RAM from auto to the correct voltage plus .05v and RAM timings specified for the RAM. You can use CPU-Z to see what the CPU vcore is suppose to be. It is often shown in the BIOS as the default voltage also.

I'd also run some stress tests to see what Load Line Calibration (LLC), setting holds the vcore voltage the closest to what you set in manually. LLC seems to not work well on many mobos and as a result the vcore can drift all over the place under heavy CPU load as in video games or stress testing. This can cause undervoltage, overvoltage and even CPU overheating under load.

Then I'd use OCCT or other software to monitor the CPU frequency, voltage and core temp when you run P95. This will also tell you for instance if the mobo VRM circuit is overheating and cutting the CPU frequency and voltage.

If you want to run manual mode and set more parameters manually the following has worked well for me and other FX-8000 users but it's only a guide as each CPU and mobo are different so what works for one does not work for all.

NB frequency = 2600 Mhz.

CPU-NB voltage = 1.325v

HT Bus = 2600 MHz.

HT voltage = 1.25v

These along with the latest BIOS tend to work for many people even when overclocking into the 4.7+ GHz. range. Naturally with OC'ing the CPU higher you can expect the need to increase vcore significantly for 100% P95 stability. You often can get 90% stability in P95 with the default vcore which is in the range of 1.325v but varies by CPU. It can take considerably more vcore in the 1.4+ volt range for 100% P95 stability when OC'd.



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Technical ignorance is NOT a destiny it is a choice. Do your homework so that you can make technically informed decisions and not be duped by advertising hype or mis-information stated as fact when its not.


 



Edited: 01/21/2014 at 05:23 PM by AMDforMe
 01/22/2014 04:53 AM
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camaroguy1998
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Originally posted by: VWM Are you already installed the windows hotfix for Fx 8350?

 

Install this one first - Windows6.1-KB2645594-x64 - Then restart.

 

http://support.microsoft.com/kb/2645594   

 

Install this one after restart - Windows6.1-KB2646060-v3-x64

 

http://support.microsoft.com/kb/2646060

 

 

 

 

Thank You VWM!

I installed the 1st Hotfix and decided to check it out and so far its been running Prime95 for 3+ hrs with no errors!

Thanx to everyone for your help!

 01/22/2014 10:02 AM
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AMDforMe
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The Windows hot fixes are to improve Windows performance as the scheduler and core parking are not optimized for FX processors. They should not be the cause of your FX-8350 instability but they can show a small ~5% on average improvement in CPU performance.

With Windows there is always the posssibility of bad code causing system issues. Microsucks may have also used these hot fixes to patch some of their horrible code and not told anyone?



-------------------------

Technical ignorance is NOT a destiny it is a choice. Do your homework so that you can make technically informed decisions and not be duped by advertising hype or mis-information stated as fact when its not.


 



Edited: 01/22/2014 at 10:09 AM by AMDforMe
 01/22/2014 12:07 PM
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camaroguy1998
Peon

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Originally posted by: AMDforMe The Windows hot fixes are to improve Windows performance as the scheduler and core parking are not optimized for FX processors. They should not be the cause of your FX-8350 instability but they can show a small ~5% on average improvement in CPU performance.

 

With Windows there is always the posssibility of bad code causing system issues. Microsucks may have also used these hot fixes to patch some of their horrible code and not told anyone?

 

That would not surprise me! Either way I am quite a bit happier that I dont have a bad processor!

I stopped Prime95 at 10 hrs. 17 mins with no errors!

I believe with the tweaks you suggested and the hotfix VWM suggested my troubles are behind me!

 

Thank You guys!

 

 01/22/2014 01:30 PM
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AMDforMe
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Sounds good.

AMD does a very complete testing of the CPUs just before they are packaged. It's extremely rare for them to ever go bad unless abused. With multi-core CPUs you will always have some variation in core performance but they will always run stable at the frequency AMD has set them for as long as the rest of your system hardware and BIOS settings are correct. They always leave a safety margin.

Enjoy!



-------------------------

Technical ignorance is NOT a destiny it is a choice. Do your homework so that you can make technically informed decisions and not be duped by advertising hype or mis-information stated as fact when its not.


 

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