Wasted some time recently looking at an HP Compaq NX7300 laptop, with Vista, that was running very slow.
No, not just normal Vista sluggishness. Really slow, as in you click the Start menu, wait a bit, and eventually it opens.
Temporarily disabled everything we could think of using msconfig (System Configuration Tool), still slow.
Checked the event log for disk errors, nothing wrong.
All very tedious as any actions took much longer than usual.
Found someone with the same problem on HP’s support forum here – but as so often with the Web, no solution is reported – though the guy does say, “can I assume that the cooling / cpu / power is defective”?
Called HP, and the guy diagnosed a faulty hard drive, though I was sceptical since his argument was that the self-test completed more quickly than expected, though it did not report any errors.
While scratching my head over this, I recalled that this laptop has what HP calls a “Smart AC Adapter”, which has an annoying proprietary connector featuring an additional central pin. According to this thread it actually supplies two separate power lines. The discussion includes this remark:
I tried to substitute the original HP AC adapter, with a general purpose AC adapter, applying a resistor divider between input cylinder- central pin-output cylinder, in order to get the second voltage. But the laptop did not function normally: it was very slow
and someone adds
The slow function of the system with the alternative power source may be due to the system’s picking up a low voltage on the ‘monitoring’ pin. This would indicate a low battery or weak charger and the system responded by cutting back on CPU/mainboard frequency to conserve power.
Could this be a clue? We started the laptop on battery power; suddenly it worked fine again. Plugged in the power cable, it slowed down. Removed the power cable, it speeded up again. Bingo.
New power supply is on order. It occurs to me that this could still be a problem with some internal connection, but I’ll be surprised if the new mains adapter does not fix it. Just occasionally the reason for a slow computer is nothing to do with Windows.
I have also seen very slow systems because of broken gfx drivers. One time I updated the ati drivers on my xp system, after reboot, the startmenu would take 10 seconds to open (welcome screen animations and things also very slow)..reverted back to old driver, problem gone.
This is very interesting. I work in tech support for an ISP and one of the main call drivers is slow speeds of the internet. 99% of the time we can pinpoint the issue to the customer computer but I would never have thought the power supply could cause it
We’ve had EXACTLY the same issue but in XP. We look after 50 odd HP laptops (not nx7300) but they are the business notebook rage, mostly nc6320.
Came across this problem with one or two of the laptops and we were thrown by how a power supply could cause CPU to run high. We ended up buying new PSUs. Funny thing was that one of the laptops had a new PSU which we had recently replaced.
hope you’ve solved it.
Also been struggling with this exact same issue with my NX7300, but I have not been able to localise the problem to my satisfaction.
Slow on AC power, normal CPU speeds on battery, same problem on Windows XP and Linux Fedora 8, even slow when selecting OS with Grub. So definitely a hardware problem.
I have logged the question with HP but they never responded.
Problem seems to start when I use standby/hibernate but abusing the power supply (whacking it, for example) also seems to help.
I suspect you’re right to suspect the power supply but something tells me that there is something else to it as well.
Did everything come right after you replaced the PSU? has the problem ever recurred?
Have you tried measuring the PSU voltages – centre pin as well as main supply – on faulty and non-faulty units? I’ve not been able to do that yet, but it would be interesting.
Tim
Tim, we did try and noticed that the voltage was a tad lower but these particular power supplies were out of their warranty so no going back to HP.
If it helps we’ve been through around 20 power suppplies in the last 12months along. Clearly there is a problem with HP about these power supplies. Some of the other problems experienced are loss of charging to the laptops as well.
Wondering if non-HP Power supplies will do a better job than the original…!
If you can get one. The problem is that non-standard centre pin.
Tim
Had the same problem with an HP bussiness laptop, slow cpu when connected to the AC, normal when on battery. Replaced the AC adapter and everything went back to normal.
I’ve the same problem with my nx7400 just last few days. Slow CPU on AC, went back to normal on battery. I’ve ordered a brand new AC adapter, looking forward to see whether it works.
It works with the new adapter!
I wonder why it happened to most of the HP laptop.
i hade the same problem. it solved by aplying 7.5 volt to the id pin(the pin in the center of the plug). zener dioda with resistor.
I made voltage divider by 2 resisteors and it works. the uper resistor in the divider is 10k ohm and the other resistor is 6.2k ohm. i got 7.5 volts on the id (centeral) pin. i used 20 volts adapter.the orginal adapter is 19.5 volts. so in this case a lower value must be used for the 6.2k resistor.
if more detailed nedded please submit comment.
I had the same exact problem and solved it by putting just 1 47k resistor between the main supply pin 19.5v to the centre pin. The voltage on the centre pin stabilizes to 7v which I guess there is a zener diode or a similar voltage regulating component inside. Many thanks for all who contributed to this thread.
Had the same issue although when I measured the voltage vetween the outside and the central pin of my Chineese replacement adapter that was giving the trouble I got 7.5 volts. I gather that these adapters (or at least the HP ones!) include power factor correction (PFC) technology, perhaps it’s a failure of components concerned with that? Will measure voltage on the replacement I’ve ordered. Dissappointing that HP did not resopnd. Makes you wonder if this additional complexity in the power supply is really a great idea.
I may be out to lunch here, but I had this same issue with an HP 2530p. I turned off ‘Fade or slide menus into view’ under the custom bar in Windows Performance Settings. This did the trick for me.
I just replaced my nx9420 adapter with the Chinesse part, but no luck, the problem still continues. ok with battery, slows with charger.
@Pedro
Beware – I’ve seen cheap Chinese power adapter replacements that are not up to spec. Try to test with an HP replacement.
Tim
Tim, I have the same problem. Did you manage to get hold of an official HP charger and did this solve the problem.
Thanks,
Kris
Kris
In the only case I know, the replacement HP charger did fix the problem.
Pedro didn’t report back unfortunately; but I have had experience of cheap Chinese adapters that do not work with this laptop, or work only for short time, so I’d suspect the power adapter in his case.
Tim
Hey guys,
Seen something very similar with my nx7300 always been ok with Vista but lately it’s been really slow. Been thinking it must be the HDD going, only had it for a little over a year. Found all your comments very usefull!
Wanted to ask though would it make a difference if I used it without the battery for a prolonged period of time?
The power issue is very specific and not just Windows running a bit slower; you would certainly notice. I doubt running without the battery would make a difference (though I suppose you are relieving the PSU of charging responsibilities).
Tim
My new (offical) HP charger arrived today, unfortuntley the laptop is still very slow when the new charger is connected. Also, the laptop does not display the charging icon (although it does charge). Back to the drawing board for me
Hello,
I have the exact same problem, in that the laptop runs really slow when charging. I have replaced the power supply a few times and this has not solved the problem.
The laptop started running slow when a power supply that was connected to it broke – I don’t know what happened, the power supply just died. My laptop has been running slow when plugged in ever since then. Could this have damaged something in the machine??
Thanks, Carla
I’m having the same problem as Tim. On battery power my nx9600 runs fine. Plug in the Power Adapter and the computer runs very slow, processor runs very fast and heats up and shuts down. Guess I’ll order a new PSU.
Thanks for everyone’s input.
Rick
I have a similar problem with my HP nx6320. When running on battery, it’s fine, but when the pc is plugged to the ac power, everything becomes sluggish.
I’ll probably have to try with a new power adapter to see whether this will help, as what Tim suggested.
On John’s query on whether it’ll be OK if it’s plugged to the ac power without the battery, the answer is no. I’ve tried it and it’s still sluggish.