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View Full Version : Bang for the buck



Ole Juul
December 9th, 2013, 11:32 PM
When I built my main desktop, just over 6 years ago, I decided to get a decent power supply that wasn't too expensive. A Zalman ZM400B-APS 400W PSU turned out to be quite nice, very quiet, and about 100 bucks as I recall. I figured it would maybe last through a couple of computers. As it turned out, it went into my recent new build and worked just fine.

Fast forward to two days ago. It's been pretty cold here. In fact it has warmed up a lot in the last two days and even then it's still only -12C (10F). Anyway, I was sitting here at my computer downstairs, freezing my hands and *** off, because this ancient leaky old building is about as warm on nights like that as city folk expect outside in the winter. This is great for computer gear. The temperature inside my computer box was showing around +12C. - a couple over the room temperature. When BANG! I heard that sound of something exploding that isn't supposed to. . . . It took me a few seconds to realize that it was my new computer (there are two other ones on at the time) and my heart sank. Eileen called down from upstairs: "what was that?" Black screen. Quad core. 8GB RAM. Silence.

After I regained my senses, I quickly diagnosed that it was the power supply which had given me the last bang for my buck. I took it apart, no smell, and I couldn't immediately find the offending part because it's packed so dense in there. I could almost have thought it was an insect getting fried, I'm very familiar with that one, but they're not nearly as loud and they do smell. Anyway, it was a short time until I had replaced it with a backup, and started looking for a replacement (http://www.newegg.ca/Product/Product.aspx?Item=N82E16817182082) from Newegg.

Things are fine again. I did a pro job of diagnosis and repair. And I think I got my money's worth out of the Zalman. It seems like an odd failure though. It's been running 24/7 for so many years mostly in a slightly-too-hot environment, and then on the coldest day it's ever encountered, in a new big and very well ventilated case, it's a gonner. Go figure.

Unknown_K
December 9th, 2013, 11:53 PM
A 400W power supply that old is probably not the best thing for a new 4 core system, especially with a gaming video card.

Newer motherboards load up on 12VDC rails, older motherboards used more on the 5VDC rails. The supply you had could do 40A at +5VDC but only 12A at +12VDC. If I had to guess you blew the 12V regulators.

Now your replacement supply is only 550W but look at the ratings, 45.5A +12VDC and 20A at +5VDC.

Ole Juul
December 10th, 2013, 01:31 AM
A 400W power supply that old is probably not the best thing for a new 4 core system, especially with a gaming video card.

Newer motherboards load up on 12VDC rails, older motherboards used more on the 5VDC rails. The supply you had could do 40A at +5VDC but only 12A at +12VDC. If I had to guess you blew the 12V regulators.

Now your replacement supply is only 550W but look at the ratings, 45.5A +12VDC and 20A at +5VDC.

No games for this puppy :) but the video card is a small step up, partly to get better Xorg support. It's a Radeon 3450 with passive cooling. I believe it eats a max of 25-30 Watts or so. My new CPU is of the 55 Watt variety. Also, I made an error in saying quad core above - it's actually a dual core Ivy Bridge (i3-3220). I can't remember what the old single core drew, but I think it was a lot more than that (90W?). All in all, the power draw on my new computer is probably about the same as my old one. After I figured out what happened, it did occur to me that perhaps I should have added some things up instead of just assuming.

You're probably right about the new demands of the 12v rails though, and the regulators getting stressed. I'll get around to digging into that blown supply one of these days so I'll know for sure. I'm hoping the new one will be serviceable for a few years. I don't change my demands much, except for generally keeping up with the times enough to not get bogged down.