Hi,

I've been trying to nail down a problem with a new system that I've built:

Motherboard: Abit VA-20
CPU: AMD Sempron 2200+
Memory: 512MB/PC2700

The Sempron was in a retail kit, i.e., I have the stock AMD heatsink/fan, and the system is not overclocked at all.

When I originally put the system together, I noticed that after the system was on for awhile, I'd hear a high-pitched whistling or squealing sound. I've been trying to figure out where this is coming from for over a week now, and have done or looked at everything that I can think of.

At this point, I am getting the sound even with everything (the drive AND the CPU fan) powered off, so it's not those.

I've also checked the toroids on the board, and the sound is not coming from them.

I have a recording of the sound at: http://members.cox.net/ohaya/AbitNoise.wav' ">http://members.cox.net/ohaya/AbitNoise.wav

The above recording was done with everything, INCLUDING the CPU fan, disconnected/powered off. The only thing that was on was the power supply.

I pulled the motherboard and power supply out of the case this weekend, and was still able to hear the sound, although it was much lower in volume.

With the board out of the case, and with the CPU fan powered off, I did some testing by physically blocking off different parts of the motherboard with some sound-deadening material, and it appears that the sound is emanating from either the CPU itself or something within the footprint of the CPU socket (there are some components under the overhang of the CPU socket).

I had wished that I had a completely different CPU chip to try with this board, to see if I was only getting this sound with the Sempron, but the Sempron is the only CPU that I have to spare.

In researching this problem, I've found a number of forums, etc. where users are reporting some kind of squealing or whistling sound. Sometimes it is something external (drive, power supply, CPU fan) or from the toroids on the motherboard, but there are also some, like mine, that just seem to come from the CPU itself.

Has anyone else noticed this with their Semprons? Any ideas of what might be causing this sound?

Thanks,
Jim

It shouldn't be from the cpu because the cpu does not contain moving mechanisms.

edwinoh,

I realize that it doesn't seem likely, but the sound is definitely coming from something within the footprint of the CPU socket. Again, the CPU fan was unplugged/off, so I don't know what else it could be, unless it's from one of the surface-mount capacitors that are under the CPU socket overhang?

Jim

See the choke and the torroid near the top of the picture to the right of the ATX power connector?

There may be some induced resonance between the 2 inductive devices causing the noise, the choke and the torroid below it.

You can try this...take an old credit card and place it between the 2 devices and see the sound subsides.

or

Turn everything off and gently push the torroid away from the choke...don't push so hard that it snaps the torroid off, you just want to move it over a bit..

Then start it up and see if the sound is still there. The same thing happens on mainboards where there are 2 torroids close together in the power section of the mainboard..common on the Shuttle an-35 ultra etc...

It happens in power transformers sometimes, that's why a lot of protection equipment has harmonic blocking in it.

MD

-------------------------
The opinions expressed above do not represent those of Advanced Micro Devices or any of their affiliates.

Physics? Ha! This is clearly magic and devilry at work. Prepare firewood! We have witches to burn!


MODERATOR

MD,

When/if this resonance occurs, is there any mechanical motion involved? In other words, do either the choke or the toroid vibrate?

The reason that I'm asking this is when the sound was present, I have tried repeatedly to press on both the choke (rod) and the toroid (iron ring) with a wooden stick, and it didn't change the sound. That's why I was concluding that the sound was not coming from the toroid (or the choke).

Jim

I'd say you wouldn't be able to see the motion...it's the 2 magnetic fields interacting if it's induced resonance...

Have you tried any other cpu's in the board...even an old duron or something...that way you can rule out the cpu or the board..

I'd also try another power supply just to be sure the PSU is not introducing anything into the system.

Last thing to try if you can get a hold of one is a mechanics stethoscope, they work well for pinpointing sounds...just make sure you put a non-conductive material on the tip...move it around to the various components and see what's making the noise.

MD

-------------------------
The opinions expressed above do not represent those of Advanced Micro Devices or any of their affiliates.

Physics? Ha! This is clearly magic and devilry at work. Prepare firewood! We have witches to burn!


MODERATOR

MD,

I wasn't so much asking about the mechanical motion because I thought that I'd be able to see it, but because I had tried to touch the ferrite ring in the toroid and the rod in the choke with with a pointed wooden stick. Assuming that the sound required something actually moving (e.g., the rod or the ring), touching them should have altered the sound, if mechanical motion/vibration was occurring.

As I mentioned, this touching did not produce any change in the sound.

I did try a different power supply (different mfr, different model), with no effect.

I also did try something similar to a stethoscope, and like I said, the sound does come from either the CPU or something under the CPU socket footprint. No sound from elsewhere.

Jim

Very strange issue...can you exchange the cpu?

MD

-------------------------
The opinions expressed above do not represent those of Advanced Micro Devices or any of their affiliates.

Physics? Ha! This is clearly magic and devilry at work. Prepare firewood! We have witches to burn!


MODERATOR

MD,

Sorry, I forgot to respond to the part of your msg about trying a different CPU. To answer your question, I didn't have a spare CPU available, so no, I didn't try that.

I would definitely agree that it's a strange problem .

FYI, I am an electrical engineer by training, though most of my work has been in software development and systems engineering lately, and believe me, I have tried everything I can think of to diagnose this problem and to determine the source of the sound.

As mentioned earlier, I know that it sounds strange that I'm thinking it's coming from the CPU or in that immediate area, but I think that I have been methodical. I keep wondering, if with the clock frequencies that are involved, maybe there's something going on in particular with the Sempron design. This is the 1st time I've run across this problem, and I have never run across anything like this problem in the other systems using Durons and Athlon XPs.

Sigh...

Jim

It's a fairly standard design, been out for some time..the Semprons are the same thing as the Bartons, Thortons & Tbred-B's...all of which are based on the Tbred B, Barton and Thorton are simply the Tbred-B with an extra 256K L2 added to the core and then they are configured appropriately.

Some of my background in this thread:
http://forums.amd.com/index.php?showtopic=43305' ">http://forums.amd.com/index.php?showtopic=43305

I'm currently an embedded firmware technician

If it was an option, maybe return the cpu to AMD directly if you have a warranty...

MD

-------------------------
The opinions expressed above do not represent those of Advanced Micro Devices or any of their affiliates.

Physics? Ha! This is clearly magic and devilry at work. Prepare firewood! We have witches to burn!


MODERATOR

MD,

FYI, I just ran across this thread on a different forum:

http://www.hardforum.com/showthread.php?t=818291' ">http://www.hardforum.com/showthread.php?t=818291

It sounds exactly what was going on with my situation...

Jim

Yeah I post there too...I still think the only way to see is to try another cpu..which you don't have or to return the processor to AMD for another one.

MD

-------------------------
The opinions expressed above do not represent those of Advanced Micro Devices or any of their affiliates.

Physics? Ha! This is clearly magic and devilry at work. Prepare firewood! We have witches to burn!


MODERATOR

MD,

Well, I shipped the system to a relative, so I definitely won't be able to try a CPU swap now .

I really liked the VA-20, and in combo with the Sempron 2200+ it was ok for me, so I'm debating building a new system for myself now, either with another VA-20 and Sempron or an MSI 939 socket board and an AMD 64. I'm thinking of using one of those tiny cases, e.g., the Antec Minuet, so power is going to be an important factor (the Minuet has only a 220W supply).

If I do decide to go with another VA-20 and Sempron, then I'll have a chance to see if I get the same noise...

Thanks again,
Jim

Sorry we couldn'y get it figured out...

Good luck with your next system.

MD

-------------------------
The opinions expressed above do not represent those of Advanced Micro Devices or any of their affiliates.

Physics? Ha! This is clearly magic and devilry at work. Prepare firewood! We have witches to burn!


MODERATOR

MD,

Thanks for trying though.

After I installed the board back into the case the last time, I left it running overnight, and I couldn't hear the sound the next morning. After that, I shut the system down just to let it cool before I packed it up.

I had ship it across the country, so that's another thing I have to worry about .

Hopefully it'll be ok, and I'll probably know in a couple of days...

Thanks again,
Jim