Compatible PSU for Lenovo M91p

Hi experts,

I have always had good luck just finding a PSU at Best Buy, which generally fit and worked fine. I got a recommendation for a new PSU for the above computer, which I purchased off the Internet. Suffice it to say, it wasn't even close to fitting.

I am looking for something in the 400 watt range, possibly a Seasonic or Antec. It really doesn't matter if you think it is good quality and will be compatible with the case.


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Gary CaseConnect With a Mentor RetiredCommented:
Since you have the full tower version of the M91p, I suspect it uses a standard ATX unit (or possibly an SFX unit).    Measure the "end" of the power supply and note the dimensions.

If it's 3.4" x 5.9" then you have an ATX unit.   This would be a good choice in the 400w range:

If it's not an ATX unit, post the dimensions and we'll find you a good unit :-)
I assume your M91p is a small form factor...
The ThinkCentre M91p is a proprietary chassis, and you won't be able to use a power supply off the shelf.

You'll most likely need Lenovo P/N 54Y8824. I'd check around - you should be able to pick one up for under $20.
dbruntonConnect With a Mentor Commented:
There are three form factors for the Lenovo M91p.

See and the diagram quarter of the way down the page.

Which one is yours?

If you've got the one of the small ones chances are that it is a proprietary power supply as suggested by Itechsolutions.
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Bert2005Author Commented:
I apologize for not listing that. It is the largest form factor. Probably why the recommendation from my friend was MUCH too small.

I am OK paying up to $60 or $75. If that would be the right one.

Oh, and thanks for the responses.
Gary CaseRetiredCommented:
I don't think the M91p uses a proprietary form-factor.    It appears to use a standard TFX supply.    I can't find a 400w unit in that form factor, but here's a high-quality 350w Seasonic 80+ Gold certified unit:

Just to be sure, check your current PSU's measurements -- a TFX unit should be 3.3" x 2.5" x ~ 6"  (the depth may vary a bit, but the 3.3 x 2.5 should match).
Bert2005Author Commented:

This is the one I bought, and it doesn't fit.
Can you post the measurements of your power supply?
Bert2005Author Commented:
Will do, thanks Gary. At least I am calling it a PSU and not a battery, lol.
Bert2005Author Commented:
Definitely the tower on the right. A tip, if you ever want a second DVD, have them install it before they ship it. If you install a 3rd party one, it will install and it will work, but it won't fit flush. You just have to trust me on that one. Sorry, just a bit off the track, lol.
Bert2005Author Commented:
With direct measurements it was:

Height 6 inches

Width 3 1/2 inches

Depth 5 1/2 inches
Gary CaseRetiredCommented:
Sure sounds like an ATX unit.
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