Laptop speed reduced by wrong adapter

[Diggs]

I recently pulled an old HP Probook 5310m off the shelf to turn into a "Pandora" machine. I grabbed a true HP adapter, plugged in and booted up. The boot took absolutely forever. Maybe 10 times normal. I eventually got Taskmaster up and it showed CPU and HDD in the 20% utilization. CPU running at .77 MHz. Really? Why the slowness? I dinked around in the crappy BIOS screens they used back then looking for the clock multipliers and other assorted switches and came up with nothing. I tried new memory, SSD, and BIOS/battery resets, every trick I could think of. Still nothing. Fine! Off to the recycle center with it! Still - I wanted one last look in the BIOS first and since I had tossed the HP power adapter back in the box I used the universal adapter on the bench. ShaaZam! Full speed ahead. Everything worked fast and great! Couldn't believe the power adapter could limit performance so severely without even notification.

Anyways - sorry for the ramble but thought I'd add to the knowledge base a bit since I hadn't seen this mentioned anywhere ever. I've been notified by Dell machines that the adapter was not correct, but I've never seen performance hampered so severely.

 

[timeshifter]

That's weird. Did you put a voltmeter on both adapters? Maybe the bad adapter was putting out insufficient voltage?

 

[Diggs]

That's weird. Did you put a voltmeter on both adapters? Maybe the bad adapter was putting out insufficient voltage?

I didn't. Voltages are hard to grab unless the adapter is under load. I don't have an adapter to patch in while it was running. I'm just glad I'm not imagining things. I knew I put that laptop away in good running order. It impressed me at the time at how well it did for a Core2 Duo.

 

[trevm999]

I didn't. Voltages are hard to grab unless the adapter is under load. I don't have an adapter to patch in while it was running. I'm just glad I'm not imagining things. I knew I put that laptop away in good running order. It impressed me at the time at how well it did for a Core2 Duo.

It's amps that you need to measure inline under load, unless it's a 'smart adapter' that only puts out the correct voltage when connected.

 

[sapphirescales]

The problem is Intel SpeedStep. Simply disable that in the BIOS and you'll get full speed even if you use an adapter without enough watts. This happens with Dell Latitude's that require a 90w adapter when you use a 65w. They won't charge, and the CPU gets reduced in speed over 90% by Intel SpeedStep.

On a related note, I once sold a Dell Latitude to a customer a few years back. The cursor would randomly jump around and the touchpad was all screwy...but only when plugged in. I changed the adapter and it worked fine. A defective adapter can cause all sorts of weird problems.

 

[Diggs]

The crappy BIOS screens on that laptop make no mention of or give access to SpeedStep. The BIOS is GUI based (see below) with almost no options. Thing is, after the 90 watt bench charger was done charging the battery the 65 watt HP charger had no problems..