ATX or Micro ATX????

[burnselk]

How does a ATX case differ from a Micro ATX case?

I have a HP Pavilion model 7955 and it's a small tower (only 14.5" high).

Today the techie on "HP Live Chat" told me I have an ATX case, not a micro ATX. But for some reason I had in my mind that I had a Micro ATX because of it's size. So I'm confused as usual and need your help to set me straight.

The reason I'm asking is I want to upgrade my little 200 watt power supply (Bestec ATX 1956D) to at least 300 or 350 watts.

My current Bestec PSU measures 5.9" W x 3.4" H x 3.9" Deep and that sucker is so tight in the case I need to get an exact "same size" replacement.....or it just won't fit in my case. No foolin....anything bigger will not fit.

1. What's a good brand of PSU? Who sells them for a good price on line?

2. Do all PSU's have the same output voltages and amps?

3. Do all mobo's require the same voltages/amps? If not, how will I determine what I need?

4. Besides fit....what should I look for in a new PSU?

I need a little help from my friends.........

Thanks guys.....and yes I'm still screwing around with this 4+ year old HP.

[Yawgm0th]

Re: ATX or Micro ATX????

Micro ATX is simply a sub-form-factor of ATX. It's meant for smaller cases, however it is also used for budget cases that are sometimes the same size or larger than ATX cases. Micro ATX motherboard will fit in ATX cases, but mATX cases will not take ATX boards.

1. Antec, Enermax, Fortron/FSP Group/Seasonic/Sparkle, OCZ, and PC Power and Cooling are among the better case brands. They probably get more expensive in that order. You'll probably end up with Antec or Fortron.

2. Voltages yes (for the most part), amps no. PSUs will be listed with amperage ratings for each of the rails.

3. It's not that simple, yet at the same time it's more complicated than that. Your motherboard doesn't really matter much as far as power requirements go. I'd say don't worry about it. The only thing you do need to pay attention to is the number of pins on the motherboard's power connector. If it is a 24-pin connector, make sure you get a 24-pin PSU. Given its age, it's highly unlikely that it's 24-pin, but then most PSUs come with a 24-pin connector with 4 detachable pins.

4. Wattage and amperage ratings as well as user reviews are what you look for. Modern (sockets 754/939/AM2 478/479/LGA775) systems are going to need higher amperage ratings on the 12v rail, especially if you have a powerful add-in video card. Older systems, especially socket A, need more amps on the 5v rail. In addition to ratings, make sure that either a reputable web site or a sizable amount of buyers have given the PSU positive reviews. For example, if you're shopping on Newegg.com (and if you're in the U.S., you should), check the user reviews.

[wayout44]

Re: ATX or Micro ATX????

Even though your case will only take a mATX mainboard due to its size it still uses an ATX spec PSU.

[Yawgm0th]

Re: ATX or Micro ATX????

I'm guessing Wayout looked up the specific model for that. If so, he's right. I took your word for it, but I know that many cases, especially ones from computer OEMs, are mATX but still take standard ATX PSUs. I've worked with a number of Gateway models like that.