Core Duo 'hiss'/'whine' - possible new findings

[BatBoy]

After receiving my Inspiron E1705 I noticed that a 'hiss'/'strange electrical whine' was evident when the unit was running on battery power. This noise is more evident when the unit is in the following state: Partially discharged battery, powered off and plugged into AC power for charging.

After several failed attempts to get this answered (Dell's typical response is its a bad fan bearing), I decided to troubleshoot this a bit more on my own.

After several reboots and hardware removal/replacing, I have ruled out the following: Battery, AC Power Adapter, Hard Drive, Memory and CD/DVD internal drive.

I have discovered that the 'hiss'/'electrical whine' appears to be directly related to the 'C' state power transition settings in the BIOS (Dell initial release ver.A00).

My findings:

1. Checked current CPU 'C' state BIOS setting. The factory default on the E1705/9400 is set to 'C4' (Allowing the CPU to utilize C1, 2, 3 and 4 sleep states).

2. Setting this to 'C1 only' and rebooting resolved the noise issue.

3. Setting to 'C2' eliminates also eliminated the hiss.

4. When setting to 'C3', there is a very faint noise. This is very hard to detect and is 'acceptable'.

5. Setting the state back to 'C4' causes the noise to return.


This leads me to believe there are two possibilties:

1. There is a problem with the way Dell's A00 BIOS for the E1705/9400 implements 'C' state power savings. This seems to be the most likely explanation.

2. There is a problem with the Intel Duo Core CPUs (I dont believe this very likely, but it might be a possible since Mac owners are hearing a hiss).

If it turns out to be a BIOS implementation issue, this needs to be brought to light so Dell will get on the ball and fix it. I (along with so many others) didn't pay for an Intel Duo Core that was crippled in respects to the power savings area.


*Others who have noticed this noise, please take time to confirm my findings with the C state changes. Post your results here.

Related threads:
http://forum.notebookreview.com/showthread.php?t=48890

http://forums.us.dell.com/supportfor...date_ascending

On the other hand, I could just be nuts and its just my lappie having issues... hahahahaha

[BatBoy]

Well, after a two hour chat with Dell Tech Support, a service tech is being dispatched to replace the mainboard and CPU.

I still think its an issue with the way Dell is implementing the C states. But if it corrects the problem then I'll be happy.

Anyone else who is having this issue should contact support ASAP. The noise/hiss is not normal.

[Jefflaw77]

did you ever get this problem fixed?

[j4y_7]

This was also a problem on Pentium M's. Some fixes that worked for me on my M140 & E1405 include:

According to Dell, this is "normal." It's also a problem with several other models, not just the E1405. Some "fixes" include...

Fix #1: Disabling Power Management in certain Devices
1.) Go into Device Manager
2.) Look for Bluetooth Devices & USB Root Hubs
3.) Right click -> Properties -> "Power Management" Tab
4.) Uncheck "Allow the computer to turn of this device to save power."

That should fix the problem. For me, all I had to do was disable power management on the Bluetooth chip. For others, disabling power management on the first USB Root Hub works. So you do'nt have to disable power management on all the devices. Play around with it and see what works.

Fix #2: RMClock
1.) Download and install RMClock here
2.) Go to "Management & Profiles"
3.) Check "Run HLT Command when OS is idle"

With this fix enabled, CPU usage will constantly be showing 100%, but don't worry, the actual CPU usage can be measured on the graph/icon in the taskbar

[Deadbolt360]

Originally Posted by BatBoy

1. There is a problem with the way Dell's A00 BIOS for the E1705/9400 implements 'C' state power savings. This seems to be the most likely explanation.

Well, I updated my BIOS to revision A01 and I have had no problems.

http://support.dell.com/support/down...&fileid=167266