Date: Sun, 27 Jan 2002 21:57:21 -0700 From: "Charles Burns" <burnscharlesn@hotmail.com> To: TD790@aol.com, mav@wastegate.net Cc: questions@freebsd.org Subject: OT: Power supply, was 64-bit PCI mobos Message-ID: <F155bdxHMh3LqPg33I60000b52c@hotmail.com>
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> > > > > >apologies if they are warranted, but your implication that it might be > > >acceptable for a MB to spontaneosly reboot with a 180W P/S that is >spec'd > > at > > >less than 150 was so ridiculous that It needed to be quashed. > > > > > >Anyway, eat the poison berries if you'd like. Those that care have >the > > info > > >they need. > > > > if it produces under it's rated ammount, if it is lower than the > > motherboard requires, all kinds of funky shit can happen. > > > >Ah, but since 180W is clearly above 150, it not clear exactly what your >point >is? TD790@aol.com, please read the replies before deciding that everyone else is incorrect. I have to presume that you did not read them in whole, else you would not have made that statement. Just to clarify, and as I stated earlier, a power supply that is labeled "X watt" (say, 180W or 150W) does not /actually/ output 160W or 180W. It's like rating speakers...Do you really think that $20 pair of 2" generic speakers on Joe's hardware sales site can handle 500W of power, when a 12" subwoofer from Klipsch or Martin Local is rated at 450W? There is a large difference in the actual, real-world output of a cheap 150W power supply and the output of an excellent 150W power supply. As I also stated, a power supply rather at, say, 400W does not necessarily supply more (or more stable) power than a power supply rated at 350W or 300W. Again, if the specs of a motherboard with certain components call for a minimum of a 150W power supply, **those specs may and probably do assume that the 150W power supply in question is a *quality* power supply.** Here is a real-world example: Leadman Electronics makes power supplies that suck. Their model LP- RD400 is *rated* as having a 400W output, but if you take the combined total real output of the 3.3v and 5v lines, you get 155W. (3.3v is important for powering the processor[s] and 5v is important for hard drives). Now, take the Antec PP-253x. Antec makes power supplies that *do not* suck. Their PP-253x is *rated* at 250W. Its actual power output (actual output is what matters, if you didn't know) is 135W. Strangely, that is quite close to the "400W" power supply above--yet the rating is much lower. Begs a question, doesn't it? That skims the *actual* vs. *real* output factor. Now, onto stability: A system with a Seagate Cheetah 10KRPM U2W SCSI hard drive, NVidia Quadro vid card, and a few other semi-common parts, was assembled to run a stress test on these and other power supplies. More info here: http://www.anandtech.com/guides/showdoc.html?i=1128&p=12 The Antec "250W" power supply was able to complete 95.5% of the 110 test runs performed on the system without crashing. (that's 2 or 3 crashes. This is a stress test, so crashes are supposed to occur) The "400W" Leadman power supply was able to complete ZERO. That is, the 400W power supply caused the system to crash 110 out of 110 runs. To derive that information, which you can probably do yourself but just in case, that means that a power supply with both a higher rating and a higher actual combined output could not keep a system as stable as a higher quality power supply with a much lower rating and a lower actual combined output. Do you understand now? Your 180W power supplies in the systems may be poorly built. They may be Leadman power supplies, or may be made by one of the dozens of other manufacturers that make power supplies as cheap as possible without regard to quality. Many (most?) OEM's build systems with the cheapest possible parts so that they can put a faster CPU or more RAM into the system--because the uninformed generally look only for those figures (CPU clockspeed and RAM, not quality and certainly not brand of power supply) Power supplies can be unstable because of poor quality components (especially capacitors); poor filtering of incoming power (making each dip or spike in power cause a crash...or worse); overheating (many manufacturers user terrible quality sleeve bearing fans which often die within a year or less--and a dead fan means a flaky or dead power supply) and many other factors. So, to reinterate--the power supplies may have been cheap and, if so, may very well have been the cause of the crashes. Again: *Good* 150W or 180W power supplies, of quality brands such as Antec, PC Power & Cooling, Seventeam, Sparkle (Acer) and others would have likely prevented the crashes if, in fact, the power supplies were at fault in the first place. Even FreeBSD crashes when using bad hardware. To rephrase, if someone were to say, "A power supply is a power supply." ...Meaning that any power supply of a certain wattage output rating is basically the same as any other power supply of the same rating), that person would be wrong. Why would AMD have a "recommended power supplies" list: http://www.amd.com/us- en/Processors/TechnicalResources/0,,30_182_869_1039^4038|1007_ATX,00.htm l ...when they could just say "Get a power supply of over xxx watts." Because some power supplies can hack it, some cannot. Wattage rating makes little real difference, except when comparing power supplies of the same class made by the same manufacturer. If I am not clear enough, here is a link to a comparison between PC Power & Cooling power supplies and others. http://www.pcpowercooling.com/products/power_supplies/insidestory/index.htm And here is another: http://www.pcpowercooling.com/support/index_faqs.htm Here is a link to some power supply terminology. http://www.pcpowercooling.com/products/power_supplies/terminology/index.htm The comparisons are written by PC Power & Cooling so are obviously biased, but they paint a good picture of the differences between good power supplies and bad ones. PC Power & Cooling, by the way, purchases and tests some of the finest power supplies on earth, and resells them at high prices. They are an excellent place to get a power supply if quality is an issue and price is not. Charles Burns _________________________________________________________________ Chat with friends online, try MSN Messenger: http://messenger.msn.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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