I know im being a little pedantic here but.....

I have found out recently, after getting a new case, that everytime i switch on or plug in a USB device my CPU temps rise by about 8C. This is the same rise caused by playing LFS!

However, I would understand this if I were constantly using the USB device in question, but I am not.

What happens is, I start a USB device (plug in USB pen or switch on Printer) and the temperature rises. However, after I have finished with these devices and unplugged or switched them off, the CPU temp stays high. This is verified by restarting my PC, as the temps immediately drop back to normal. Even after playing LFS my temps go back down to normal.

I have checked the CPU loading in task manager by checking the processes, but it just shows the usual 99% idle process. If anyone knows of particular processes that might cause this let me know so I can test.

I have tried updating my USB drivers which didnt change anything.

This is an annoying problem, but not critical obviously, so any thoughts would be appreciated!

Most onboard temp sensors arent very accurate to be honest, and it could be a glitch with the fundamental design of your motherboard that when a USB device is plugged in, it reports the incorrect temperature. I'd had this sort of thing (strangely it was with parallel ports instead), and it was verified by the manufacturer.

Quote from the_angry_angel :

Most onboard temp sensors arent very accurate to be honest, and it could be a glitch with the fundamental design of your motherboard that when a USB device is plugged in, it reports the incorrect temperature. I'd had this sort of thing (strangely it was with parallel ports instead), and it was verified by the manufacturer.

hmm, but the temperature still varies after usb, it isnt fixed.

normal is 29C, after USB is about 36/37 and it hovers around that.

Each USB device draws some power, but I am not convinced that you would experience such a sharp rise in temp. That type of jump in temp sounds like your CPU is working harder all of a sudden.

Are you saying your system is apparently running at 37C ? If so, that seems quite acceptable, in my opinion.

Like Gunn says, I wouldnt worry about it too much. Its easy to become obsessed with this sort of data.

well, like i said chaps...i am being pedantic here!

and i know 37C is perfectly ok.

but like Gunn says, a sudden jump like this is quite strange and a bit annoying.

btw, MB is MSI KT800 just incase. ill have a look to see if there are any known issues.

Quote from the_angry_angel :

Its easy to become obsessed with this sort of data.

ive caught the bug, i blame [dSRC] Gener_Al and his watercooling! my 120mm fans are more than a match........bah!

mmm.....watercooling

Looks more like the south- or northbridge has problems with the sensors and registered USB-devices.
I'm 99% sure that the real temperatures stay exactly the same with or without usb-device. You're just messing around with buggy sensor-readouts.

Vain

Did you look at CPU usage? Edit : yes you did (better read carefully before posting) :red:

I have the same kind of issue, but with MSN 7.5 (maybe cause I didnt' unlock it in the firewall). When it freezes, my CPU usage raises to 100%, and my CPU temp 42°c (AMD 64 3000+ inside), witch is near it's highest burning temp (43°c after 12mn Prime 95)

Immediately after killing or unfreezing MSN (several right click on the icon in the systray is enough), the CPU temp drops to 31°c (normal idle temp).

Maybe you have the same kind of problem, but with USB drivers?

USB is a CPU-hog.

if the temp rise is not a glitch in the bios then it may be because the usb device is beeing constantly polled, causing a higher then normal cpu load (ie, the cpu is never idle)

Quote from dUmAsS :

if the temp rise is not a glitch in the bios then it may be because the usb device is beeing constantly polled, causing a higher then normal cpu load (ie, the cpu is never idle)

iirc, usb decives ARE constantly polled, i just don't know how much cpu is involved (vs the usb controller)...

If USB make a computers so much hotter, I wonder what the temp of mine is, I have 8 USB's hooked up all the time Never have problems tho, and my comp is on for at least 5 hours a day, in weekends even longer, whole days! I think it's just an error tho.

could this be anything to do with it?
http://www.tgdaily.com/2006/02 ... atch_for_power_drain_bug/

one of people in the threads linked to that story has the exact same problem as myself. although it primarily mentions laptops, it seems as though it is XP in general. i look forward to a patch

http://www.anandtech.com/mobile/showdoc.aspx?i=2693&p=8

Here is an alot more indepth article about it, together with an explanation how to fix it. Seems intel processors are not fans of USB 2.0.

But that shouldnt cause a 8° temperature rise all by itself.
Maybe if your PSU is really weak it cant give enough power and thats why the CPU runs hotter when u plug in USB

Quote from Noccy :

http://www.anandtech.com/mobile/showdoc.aspx?i=2693&p=8

Here is an alot more indepth article about it, together with an explanation how to fix it. Seems intel processors are not fans of USB 2.0.

But that shouldnt cause a 8° temperature rise all by itself.
Maybe if your PSU is really weak it cant give enough power and thats why the CPU runs hotter when u plug in USB

thanks.

i might try the registry edit. im pretty sure its not my PSU though, its a decent 350watt Antec one (iirc).

Just a few questions that spring to mind:

What CPU are you using?
Does it have adjustable vcore?
Does the vcore change with load?
Does the vcore change when you plug in the USB?
Have you checked other parameters that may cause the temp to rise? (clock frequency, fan speeds)
Does plugging in the USB cause performance drops in Benchmarks like superpi?

Doesn't matter J.B.

I applied that registry fix from the link Noccy provided, so thanks Noccy

All works perfect now, yay!

Glad you fixed it. I had a quick look at the link and it seems the USB device indeed stopped the system from lowering vcore and multiplier so I was on the right track with my questions. So which CPU were you using? Is this an Intel specific problem?

Athlon 64 3000+ Newcastle core @2Ghz (not OC).
I dont know if the Core Center that comes with these chips alters anything on the fly, but voltage core, FSB and other gubbins can be tweaked manually using Core Center. I just leave them be as my MB doesnt lock out the RAM and AGP, so i leave my CPU standard.

My 3000 ALWAYS bugs out on me. My idol I KNOW is around 32 C when right now as I type this it's at 39, which seems extremely odd, since all I have is music playing, mozilla, and aim. I don't even use on board audio. My guess is faulty mobo sensors.

Quote from xapexcivicx :

My 3000 ALWAYS bugs out on me. My idol I KNOW is around 32 C when right now as I type this it's at 39, which seems extremely odd, since all I have is music playing, mozilla, and aim. I don't even use on board audio. My guess is faulty mobo sensors.

Maybe it's the CPU diode. This temp changes instantly, according on the CPU usage.
Having a 3000 too (@2500Mhz, perfectly stable), normal CPU temp is 31°, and full burning is 43° (after 10mn). CPU usage at 100% for 1 or 2 sec is enough to raise up to 39°

Quote from mosquito25 :

Maybe it's the CPU diode. This temp changes instantly, according on the CPU usage.
Having a 3000 too (@2500Mhz, perfectly stable), normal CPU temp is 31°, and full burning is 43° (after 10mn). CPU usage at 100% for 1 or 2 sec is enough to raise up to 39°

My temps are pretty much identical to yours when on 2GHz stock clock. Only my idle is slightly lower. Mind you, I don't even use the Core Center to control CPU fan speeds now. I have an Asetek Vapochill Micro High End fan with an external speed control, so it is just constant at 2500rpm.

When I first put my PC together I would keep an eye on temperatures and fan speeds. It would give an alarm sometimes and I was worried my CPU would fry. Then one day I formatted and never reinstalled the monitering software...and there hasnt been a single alarm since :P sometimes, ignorance is bliss.