I love the SFF cases of the IBM/Lenovo ThinkCentre desktops. I acquired one of these computers second-hand recently and plan to upgrade it to suit my needs. I've run into a lot of frustration in trying to decide on a power supply upgrade. The case will only fit a microATX power supply and the IBM/Lenovo replacements provide no more than 225W.
There are a few microATX PSU available that might fit in this small case. HOWEVER, the configuration of the case is that the placement of the power cord socket in the PSU is essentially "proprietary." That is, the plug/socket is set in the rear panel of the case is in its own little hole, unlike generic CPU cases wherein the PSU fits in a rather large opening in the rear of the case.
All that being said, because I want to upgrade to a 400W PSU, I am thinking of going to a hardware shop (Home Depot, for example) and having them cut an opening in the rear panel of the SFF case, large enough so that any brand microATX PSU and /plug/socket will easily fit. Is this a viable idea, or is it DANGEROUS?
IBM ThinkCentre M52, Model 8212
P4, 3.0 Ghz
2 Gig Ram DDR2-4200
nVidia 8400GS 512mb
The reason why they do not do more than 225W is because the case design sucks and they have major heating issues which blow out their capacitors. DO NOT mod the case to use any performance parts as you will bake them and break them. In fact they are such a problem that we no longer use them at my work (Cincinnati Computer Cooperative) because they ALWAYS come back with problems. If you require more than the 225W then get a proper case with good airflow and start over in that, or at least upgrade the motherboard with something that has solid state caps inside which can take the added heat you are putting in.
As for the mod, no, it is not particularly dangerous to do (as the PSU housing will protect the user from frying themselves), it is just a generally bad idea because it was designed for a particular configuration and you will run into other issues down the line by modifying it.
I agree with both jdenova007 and CaedenV. It's better to get a new case, and yes, there are many microATX cases out there that will allow for a larger capacity power supply. As CaedenV also said, "they have major heating issues which blow out their capacitors.". It's not worth it. Buy a new micro box and you'll have many more options! Good luck!
P.S....Sometimes box vendors will also sell power supplies for the boixes they sell. That way you'll know what will/won't work in your new box.