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Discussion Starter · #1 ·
Ok a little background here. Since building my 3930K rig, I've consistently had an issue where my FSB is less than 100 MHz. Typically, it floats between 96.80 MHz and 98.69 MHz. When I say "floats around" - it will vary on every tick/second in CPU-Z and HWiNFO x64. Even if I bump my BCLK frequency in the UEFI BIOS up to 101-102 MHz, it still hangs in the 96-98 MHz range.

The BIOS settings are pretty much stock with the exception of setting XMP Profile #1 for 8-8-8-24-1.5v-1.3v RAM settings and bumping the turbo ratio up to 42. The BCLK jumping around happens even if I set the memory profile back to JEDEC Auto and the turbo multiplier back to Auto, so I know that's not affecting the issue at this point.

Any ideas what's going on? System is solid as a rock stable in prime95, Handbrake, gaming, etc. My previous ASUS boards were dead-on 100 MHz bus speed +/- 0.1 MHz. This P9X79 is the first one I've had where the bus speeds jiggles around so much.

System specs are in my rig profile.

Greg

P.S. Ignore the multiplier and core speed in the CPU-z image, I have all of the SpeedStep and power saving features enabled as default, and the screen shot caught me at a wierd multiplier.

Created with GIMP
 

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Discussion Starter · #2 ·
Bump.

Nobody's experienced this before? Last night, I spent about an hour going in and out of the UEFI BIOS adjusting various settings to attempt to make an impact on the bus speed. Among the things attempted include:

- Adjusted the CPU Load Line Calibration to Medium, High, and Ultra High, with no effect at all.
- Adjusted the VCCSA Load Line calibration to Regular and HIgh with no effect.
- Adjusted the CPU Power limit to 100, 110, 120% with no effect at all.
- Enabled and Disabled CPU Spread Spectrum with no effect.
- Enabled and Disabled PCIe Spread Spectrum with no effect.
- Set memory back to default JEDEC settings (DDR3-1333, standard voltages and AUTO for all settings), no effect on bus speed.
- Reloaded Optimized BIOS settings, ran bone stock BIOS configuration, no effect on bus speed.
- Installed the next earlier BIOS version from ASUS web site (3203) with no effect on bus speed.
- Tried older (1.59) and loaded the newest (1.63) x64 versions of CPU-ID just in case. No effect on bus speed.

Bus speed wavers between 96.24 MHz and 98.35 MHz. Even if I set the BCLK to 101 or 102 MHz in the BIOS, it still reads as 96-98 MHz in CPUID.

Board is 100% stable, but I have no faith in the OC clock speed on my CPU without knowing for sure if the bus speed is accurate. I'm about ready to get a Rampage IV Extreme just to see if I'm going crazy or not. LOL.

Greg
 

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Discussion Starter · #3 ·
Further experimentation indicates this may just be a problem with CPU-Z and HWiNFO64 and how they read the bus and core speeds on my P9X79 board. See the screen shot for details, but Core Temp 1.0 RC4 shows my bus speed as 100.01 MHz and core speed at 4000.46 MHz with a 40x multiplier, just as I have it set in the UEFI BIOS. CPU-Z and HWiNFO64 (both the latest version) show core speed in the 3892-3900 MHz range, and CPU-z shows bus speed floundering between 96 and 99 MHz on every tick.

I am going to open a ticket with CPU-Z and HWiNFO to see if they have any insight into this issue.

Greg
Created with GIMP
 

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Discussion Starter · #4 ·
I've been going back and forth with CPU-Z developer/support on this, and the conclusion is that there must be some timer that's out of spec on my particular P9X79 Deluxe that is causing the bus speed to wiggle around. So, I did what any other OCD diagnosed person would do -- ran out to Micro Center and bought a replacement board and gave my P9X79 Deluxe to the wife with a brand new i7-3820 to replace her 2600K.

The new board I bought is a P9X79 WS. Basically the same board as the Deluxe, but with a different PCIe layout that permits Quad SLI, a few less USB 3.0 ports, a few more USB 2.0 ports, 9-pin serial port, and a few other minor differences.

I swapped my 3930K out of the Deluxe and onto the WS, allowed Windows 8 x64 to reconfigure for the new board, and fired up CPU-Z. Poof. Same exact problem, bus speed jumping around from 97-99 Mhz.

Rebuilt the wife's PC, put the brand new i7-3820 on my old P9X79 Deluxe, and fired up Windows 8. Didn't even have to reinstall or reconfigure the OS after pulling out her P8Z68-V Pro Gen2. Talk about a fast swap. LOL.

Guess what, CPU-Z shows rock solid 100.01 MHz in her box, with the new CPU. Now I'm down to wondering if it's my 3930K that is causing the bus speed to sag and jump around, or if there is another peripheral at fault. Time to yank all the USB connections, extra SATA devices, fans, and maybe reinstall Windows 8 onto an old HDD just to see if the issue goes away.

Sorry if it seems like I'm babbling in this thread all to myself. I'm hoping someone will jump in and claim a similar experience that might shed some light on this. I'm particularly curious if anybody has a 3930K, Windows 8, and P9X79 variant that has tried CPU-Z and can report if their bus speed is stable, or if it's variable like mine.

Greg
 

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Discussion Starter · #5 ·
The problem has been identified and fixed!

Enabling Hyper-V role in Windows 8 Pro apparantly causes this bus speed reporting issue. Perhaps there's some sort of hardware abstraction layer going on under the covers when Hyper-V is enabled that causes CPU-Z and HWiNFO64 and a few other utilities to read a synthetic bus speed instead of the actual hardware registers.

Mark this thread closed!

Greg
 

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Greg,

thumb.gif


You just saved me a few precious hours of troubleshooting!
 

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Quote:
Originally Posted by hammong View Post

The problem has been identified and fixed!

Enabling Hyper-V role in Windows 8 Pro apparantly causes this bus speed reporting issue. Perhaps there's some sort of hardware abstraction layer going on under the covers when Hyper-V is enabled that causes CPU-Z and HWiNFO64 and a few other utilities to read a synthetic bus speed instead of the actual hardware registers.

Mark this thread closed!

Greg
Thanks Hammong so much, I got the same situation, I try to search google, and read your post, It help me to save money
thumb.gif
, because I want to change motherboard to check this issues
biggrin.gif
 

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Quote:
Originally Posted by hammong View Post

The problem has been identified and fixed!

Enabling Hyper-V role in Windows 8 Pro apparantly causes this bus speed reporting issue. Perhaps there's some sort of hardware abstraction layer going on under the covers when Hyper-V is enabled that causes CPU-Z and HWiNFO64 and a few other utilities to read a synthetic bus speed instead of the actual hardware registers.

Mark this thread closed!

Greg
I cannot thank you enough! Made an account here just to do this
smile.gif
. I've been going nuts about my i5-2500k being at 98.27 x 47 = 4.619 GHz instead of rock solid 4.7 GHz. I seriously thought this had to do with my motherboard (ASRock Extreme3 Gen3), although I had it for 3 years now and it only started happening after installing Windows 8.
 

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OMG, I have been trying to figure this out for like two weeks, thank you.
 

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Another Hyper-V user enlightened by this insightful thread. Thank you!
 

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I am having the same issue on my Asus p8zz77-v pro board. Cpu-z, realtemp showing at 99.77 at any loads. I am running Windows 7 and I do not see this 'Hyper-V' on here.
 

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Quote:
Originally Posted by hammong View Post

The problem has been identified and fixed!

Enabling Hyper-V role in Windows 8 Pro apparantly causes this bus speed reporting issue. Perhaps there's some sort of hardware abstraction layer going on under the covers when Hyper-V is enabled that causes CPU-Z and HWiNFO64 and a few other utilities to read a synthetic bus speed instead of the actual hardware registers.

Mark this thread closed!

Greg
I can't thank you enough - I joined especially to be able to say Thank you.
This saved me from spending even more hours of going mad on Google without a clear answer.
 

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RIG: Win 8.1 Pro, Asus Max V Formula (1903 BIOS), [email protected]

I have Hyper-V installed and running with the latest version of CPU-Z, 1.72.

According the the 1.67 readme file, the BusClock option was changed--> "- BusClock : Set to 1, uses the bus clock as primary clock source. Set to 0 to use an alternate method"

By setting BusClock=0 (rather than=1) in your cpu-z.ini, CPU-Z will report your bus speed correctly at 100 MHz. Otherwise you can run 1.66 where the BusClock was detected by a different method.



Hope this helps!

P.S. Removing Hyper-V did not fix the problem for me so I dug deeper.
 

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Thank you so much, like others, I finally stumbled upon this thread and this was precisely the fix!

I'm cross-linking it with a thread I had started at Anandtech. You deserve the credit, for sure!
 

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You have absolutely no idea how much grief this issue has caused me
biggrin.gif
That'll teach me to rely too much on a single tool from now on.

The bclock, CPU, RAM, and Uncore frequencies are all way off and will fluctuate erratically because the base clock itself bounces randomly around within a 94-97Mhz range with my ASUS Z97 Pro board.

Default CPUZ Behavior BusClock=1

Broke1.png
Broke2.png


CPUZ BusClock=0

Adjusted1.png
Adjusted2.png


In my case, enabling hardware visualization in the UEFI would cause CPUZ to go wonky as shown above, as it is required for the HyperV role to activate within Windows. It turns out as a separate issue one of my XMP profiles was not quite stable, so when I would enable hardware visualization the system would get very unstable further reinforcing my incorrect notion that this was a hardware issue.

Went ahead and crossposted on Tech report as well.
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