Marginal OEM Power Supply
in [Chips]
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From: Bill Davidsen on 19 Jun 2010 12:36 Robert Myers wrote: > Bill Davidsen wrote: >> Robert Myers wrote: > > <snip> > >> >>> I increased the memory by 50%, reinstalled the incorrectly installed >>> memory, and added a second HDD, and the machine did boot. >>> >>> I haven't used the machine much, and, in particular, I haven't used >>> the video much, but this summer I started encountering video problems >>> while trying to upgrade Fedora. >>> >>> Since I had an extra video card available, I tried changing video >>> card. My replacement video card drew too much power and the machine >>> would not even boot. The easy conclusion was that the power supply >>> was either malfunctioning or marginal to begin with. >>> >> That's a fair guess, many are sized to the need as sold. That's not an >> unfair practice, just one which should be more obvious before it bites >> you. >> > Never occurred to me that they would size the power supply to the actual > sale. That means that, even if you pay outrageous prices for a > subsequent OEM add-on, it might not work. I'd call that deceptive > marketing. > >>> The computer store is a fair drive, so I bought both a replacement >>> power supply and a very low end video card. I don't like replacing >>> power supplies, so I tried the video card. Works like magic. I'll >>> replace the power supply if I get around to it. I mostly run the box >>> remotely and I don't need fancy video. As far as warranties are >>> concerned, I can't imagine what circumstances would make a warranty >>> repair worth my time, so I don't worry about it. >>> >> Unless you have some reason to use a brick and mortar store, places >> like newegg and tigerdirect are good sources for parts. >> > A Microcenter is reasonably close, and, if you shop carefully, their > prices are hard to beat. > > **And**, if something goes wrong, I know how to find the store manager. > That qualifies as a reason for sure, didn't think "reasonably close," since you earlier said "The computer store is a fair drive," but I know what you mean, not too far to go to save a shipping cycle but far enough that you don't want to do it twice. >>> Maybe when you pay for installed upgrades, you pay for an upgraded >>> power supply. Since the memory was added to this box with no further >>> testing, it's easy to imagine that boxes might be shipped with >>> upgrades such that the power supply is often marginal or inadequate. >>> >>> Anybody have any insight? >> >> Except for gamer machines, vendors expect the cover to stay on. The >> bad memory install would have gotten a complaint from me, I doubt >> anyone ships without a smoke test, at least not anyone remotely >> reputable. I bet someone saved a bit of time by not doing it as s/he >> should. > > The default memory configuration for this machine was two sticks. A > third stick was added to this three-channel machine as an "upgrade." > > DIMM slots 0 and 2 had been installed correctly and the "upgrade" was > installed to slot 3. > I would expect that to pass smoke test, then, incorrectly installed as in not full speed rather than upside down or something, I'm actually surprised that it didn't show up working on POST and only be obvious with the cover off or using dmidecode. Or whatever the Windows tool is to get the same information. > This purchase was from a *very* well-known OEM. It's really hard to > imagine who, other than someone like me or a gamer, would buy such a > box. The only reason I don't name the company is that I know engineers > who work there. > > Robert. >
From: Robert Myers on 19 Jun 2010 14:22 Bill Davidsen wrote: > Robert Myers wrote: >> >> DIMM slots 0 and 2 had been installed correctly and the "upgrade" was >> installed to slot 3. >> > I would expect that to pass smoke test, then, incorrectly installed as > in not full speed rather than upside down or something, I'm actually > surprised that it didn't show up working on POST and only be obvious > with the cover off or using dmidecode. Or whatever the Windows tool is > to get the same information. > I would have expected it to boot, too, but it didn't. I tried to boot before opening the machine. It's been long enough that I don't remember if it got past a power-on POST and stopped at a blank screen. Maybe that would have constituted passing a smoke test. I can understand why a tester in a hurry wouldn't want to wait for Vista to boot. Since I intended to add memory, I didn't hesitate to take the cover off to see what was going on. Making what I thought would be a correct memory install fixed the problem. Robert.
From: Yousuf Khan on 20 Jun 2010 05:32 On 6/19/2010 1:57 AM, Robert Myers wrote: > The computer store is a fair drive, so I bought both a replacement power > supply and a very low end video card. I don't like replacing power > supplies, so I tried the video card. Works like magic. I'll replace the > power supply if I get around to it. I mostly run the box remotely and I > don't need fancy video. As far as warranties are concerned, I can't > imagine what circumstances would make a warranty repair worth my time, > so I don't worry about it. > > Maybe when you pay for installed upgrades, you pay for an upgraded power > supply. Since the memory was added to this box with no further testing, > it's easy to imagine that boxes might be shipped with upgrades such that > the power supply is often marginal or inadequate. > > Anybody have any insight? I can quite imagine that an OEM box would have the bare minimum power supply specs require. I mean this must be one of several reasons why an OEM box is cheaper than any box that you can put together yourself. You probably would buy a PS with a little bit of extra margin in it, and it's likely that you probably couldn't even buy a PS as low as what's in an OEM box. Yousuf Khan
From: Robert Myers on 20 Jun 2010 14:57 Yousuf Khan wrote: > On 6/19/2010 1:57 AM, Robert Myers wrote: >> The computer store is a fair drive, so I bought both a replacement power >> supply and a very low end video card. I don't like replacing power >> supplies, so I tried the video card. Works like magic. I'll replace the >> power supply if I get around to it. I mostly run the box remotely and I >> don't need fancy video. As far as warranties are concerned, I can't >> imagine what circumstances would make a warranty repair worth my time, >> so I don't worry about it. >> >> Maybe when you pay for installed upgrades, you pay for an upgraded power >> supply. Since the memory was added to this box with no further testing, >> it's easy to imagine that boxes might be shipped with upgrades such that >> the power supply is often marginal or inadequate. >> >> Anybody have any insight? > > I can quite imagine that an OEM box would have the bare minimum power > supply specs require. I mean this must be one of several reasons why an > OEM box is cheaper than any box that you can put together yourself. You > probably would buy a PS with a little bit of extra margin in it, and > it's likely that you probably couldn't even buy a PS as low as what's in > an OEM box. > I had previously noted the puniness of power supplies on OEM boxes, but not by overloading them to the point where the machine wouldn't run. I don't think that upping the RAM by 50% and adding a HDD causing a power supply overload is a reasonable expectation. Something else about this machine that is shaved very close is the thermal design. It will not run for long with the side cover removed. That wouldn't surprise me if the side cover included a duct, but there are only holes strategically placed in the side panel. The CPU has an enormous heat sink, but no fan of its own! Robert.
From: Robert Redelmeier on 21 Jun 2010 08:28
In comp.sys.ibm.pc.hardware.chips Robert Myers <rbmyersusa(a)gmail.com> wrote in part: > I had previously noted the puniness of power supplies on OEM > boxes, but not by overloading them to the point where the machine > wouldn't run. I don't think that upping the RAM by 50% and adding > a HDD causing a power supply overload is a reasonable expectation. Agreed. HDDs (especially 10k) can cause a heavy motor-start load on the 12V but should otherwise be fine. One problem with big OEMs is they are also aiming at EPA EnergyStar targets which cause them to tight-size PSUs for max efficiency. The German TuV may also have powerfactor targets. > Something else about this machine that is shaved very close is > the thermal design. It will not run for long with the side cover > removed. That wouldn't surprise me if the side cover included a > duct, but there are only holes strategically placed in the side > panel. The CPU has an enormous heat sink, but no fan of its own! There is your clue, no CPU fan -- the cover is a duct. With the cover off, air can bypass the CPU heatsink and slip straight to [from] the PSU fan. I've built machines without CPU fans, and you have to be very careful about airflow. -- Robert R |