The RM112 came from the SFF optiplex. These mid-towers "looked" to be using normal ATX sized PSUs compared to the precisions which were obviously a little bigger. So I did some searching and came across the H255E PSU which some of these mid-tower optiplexes use. (Seems they also go by PW115 and other numbers as well. Dell sure has a lot of part and model numbers for these things.) Specifically, I bought it off of eBay. It's "only" 80+ Silver but it looked like it could have been a drop in for any ATX PC. Well, I should have looked closer...
They added just a little bit of extra height too it. Same mounting holes and power connector, just a little taller. Crap, the extra height is the same as the Precisions, just hidden when looking at the back of the Optiplex. So much for a drop in. Also, the power connector comes off the bottom of the PSU, not the back. I had known this and had it been a normal height, it might have worked like that in my mini-P180. But not now. Alright, I guess I'll have to mod after all.
First, a few shots of the inside. It uses a dual PCB setup with what looks like the primary and filter stage on one side and the secondary stage on the other. I knew a fan swap was going to happen no matter what. Dell generally uses pretty crappy fans and this one was no exception. Also, it only used an 80mm fan. Other Dell PSUs using the same form factor use 92mm fans. Not sure why they didn't here.
After cutting out for a 92mm fan, I first attempted to put it on the inside like it was. It worked but the fan was right against some metal tabs on the top. So even with a soft-mounting, it would still be in direct contact. I could have bent the tabs but instead, I decided to put the fan on the outside a-la Antec CPX. No problems with soft-mounting here and I had plenty of room in my case for the extra depth. I also re-routed the main ATX power cable out the back instead of the bottom. That was easy enough. Just had to cut the hole in the back a little bigger to fit the extra cables.
If I mount it the correct way, all four screws line up just fine. But this puts the cables coming out at the front side of the case, not the back. So I flipped it over. I can only really use two of the screws now but that holds it in good enough. The last issue was that although the mini-P180 had a large enough area for the PSU, the beams get in the way of the PSU actually getting in there. So I had to cut off part of the beam to let it squeeze in.
Now for the results. I dropped it into my main PC which was using a Seasonic SS-350ET and idled at about 51W. The H255E dropped that by about 4W to 47. Nice start. Then I went and dropped it into my lowest-powered system: Pentium M 725 (1.6GHz), AOpen i915GMm-N and a 2.5" hard drive...
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H255E RM112 pico 120 pico 150 SS-300SFD SS-350ET State WAC PF WAC PF WAC PF WAC PF WAC PF WAC PF -------- --- ---- --- ---- --- ---- --- ---- --- ---- --- ---- Off 1 0.21 1 0.20 2 0.44 3 0.48 2 0.57 1 0.40 Unloaded 4 0.45 4 0.42 - - - - 4 0.77 3 0.7 Idle 18 0.86 19 0.80 19 0.92 21 0.90 22 0.92 20 0.95 Load 32 0.93 33 0.90 32 0.96 36 0.93 36 0.95 34 0.95 - picoPSU's not tested unloaded - H255E and SS-350ET ran at a different time. Unsure of possible systemm changes - picoPSU 120 using a 90W brick and tested with a different CPU (but same voltages) - picoPSU 150 using a 200W brick from a Shuttle SD11G5
The conclusion, it still took some modding to make this PSU work. But it was less than with the RM112 and produced better results in my situation. And it would still be very dependent on your case and if there is room for the extra height. If using a case with the PSU at the top and nothing in the way, it could very well be a drop in replacement. And at $26 shipped, it's a pretty good bargain.