CPU throttling with new PSU

[Stinkpadda]

Hello

I have a W510 with the 135W PSU. Or to be more precise: 6.75A @ 20V.

I work at two places, so I bought a generic 150W PSU with an adapter to fit the Thinkpad. The PSU is labeled 7.5A @ 20V, so it should have no problems running the laptop.

Still, upon boot I get the "This PSU is too weak for something something charging battery something" and my i7 is throttled to 1.2 GHz rather than the 3.06 it usually musters.

If I boot from battery and attach the PSU connector after Windows is up, it runs at full speed. And charges the battery just fine. So obviously, there is nothing wrong with the juice from the PSU.

Thus, I suspect that BIOS does something dumb. Can I override this somehow?

Friendly,

Some Dude

[RedEd12 Support Specialist - Retired]

Stinkpadda:

I would stick with the 135W PSU, which I believe is part 42T5029 and 42T5114

http://support.lenovo.com/en_US/product-and-parts/detail.page?&LegacyDocID=MIGR-74503

http://support.lenovo.com/en_US/product-and-parts/detail.page?LegacyDocID=MIGR-74504

I'm showing that adaptor as the only compatible PSU for the W510.

[lead_org Microsoft MVP Contributor · Accepted solution]

this maybe that the ThinkPad not detecting the generic adapter properly. The central pin from the generic adapter is not giving the right signal to the laptop power management firmware.

Check in the ThinkVantage Power Manager what does it say under it for the generic 150 watts adapter? is it saying 90 watts?

[Stinkpadda]

Oh, I did not realize that I could see that in Power Manager. Fascinating!

It says 90 W.

I found another thread where the central pin thing was mentioned. I am about to order a new connector tip to chop up and modify, as that is quite a bit cheaper than buying a new PSU.

Thanks to you both for the information!

[lead_org Microsoft MVP Contributor]

this is the problem with these generic power adapter... had this problem in my W510 too. I ended up just using the old 135 watts adapter of mine.

[Stinkpadda]

I am under the impression that the problem is that with <135 W power tip, the center pin is not grounded whereas for the 135 W it is, and that is what the system uses to identify the PSU.

So I ordered some extra power tips and I am going to experiment a bit. I have a second laptop that I dare put to risk when trying this hypotheis out. =)

[Stinkpadda]

Hello

Just wanted to say that I sort of fixed this problem. Details here:

http://forum.thinkpads.com/viewtopic.php?p=683172#p683172

[huberth]

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Stinkpadda wrote:

Hello

Just wanted to say that I sort of fixed this problem. Details here:

http://forum.thinkpads.com/viewtopic.php?p=683172#p683172

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Quote:

"So there you have it - if you want to modify your power connector so that the system thinks it is a full-powered unit and does not throttle the CPU, just short-circuit the center pin to ground."

Perhaps someone could sell a little adapter that connects the center pin to the ground.

Then we could use a lightweight 90W power supply unit when travelling. 

[Stinkpadda]

I'm not sure what happens to a PSU if it is subject to a load that is higher than it is designed for - can it explode or will it just brown-out or something?

I did my modification because the W510 (requiring 135W) did not recognize my el-cheapo 3rd party 150W PSU as such.

[dragon-fly]

currently im using the adapter on my 90W PSU and it went up to 135W. i didnt let it stay there for too long, idle and recharging battery on optimus its consuming around 73W at the wall, on 90W converted cheapie psu.

This psu (non lenovo) is hardly efficient though, its power factor is around 55%, so its using 105VA for 55W.

idle test, optimus quad core hyperthreaded battery charging

170W psu: 62W at the wall, 64VA, Power factor 94%

90W Cheap psu with mod cable: 62W at the wall, 113VA, Power factor 56%

with my 170W genuine lenovo adapter, under the same load, its consuming less VA, in other words, less immediate load on the equipment. Bottom line: Im going to keep using my 170W Genuine lenovo adapter for my solar powered W530. - simply more efficient.

as to what happens when a psu gopes bad, it does a brownout. ive had several super generic 3 pin any voltage adapters burn on me, they get boiling hot and burn themselves out on the inside, and produce insufficient voltage to work. other adapters i've seen simply melt into a plastic puddle of nothingness.