I recently purchased a new video card for my HP Pavilion 250n desktop, and the manual for the new card recommends that I should have a 300W power supply (as the card also draws from the PS), but my computer only has a 250W supply.
I need a larger PS (300-350W), but searching online reveals no power supplies that are specific to my computer. I do see a lot of generic units, though.
The question: are power supplies more or less standard as far as form factor, i.e. will a new PS physically fit into the space my old one occupied, or am I looking at having to modify the case, drill holes, etc.?
And if you are wondering what brand to use, I would go with Antec, Enermax, or Thermaltake. A 350 watt PS from a good brand like these is much better than a 450 watt generic power supply, much less the POS power supplies you see in HP or other large OEM’s computers.
Nope, it’s one of the more straight forward things you can do on a computer. Just make a note of what is plugged into what, such as things connected to the motherboard, if any, so you reconnect it later. Also take a moment to tie up the cables and keep things neat, it will save you time later if you ever need to access the guts of the machine to install new memory or something. Nothing is worse then navigating through a jungle.
For every accessory attached to your current power supply, write down which pin gets the black wire. Draw diagrams, use a crayon to mark the hardware, whatever, but ensure you know which way the power connector goes. Modern power connectors are mostly foolproof, but you can still fry some components by attaching the power incorrectly. When you’ve done this, remove your old PS.
Take the new PS out of its box. First things first: tie the power supply’s power cord (the one that runs to the wall) around something like a chair leg, in another room. Leave it where it is. Don’t touch it until you’ve finished attaching everything else. You will not be needing that part for the forseeable future. Forget it exists. Until you’re sure your machine is connected properly, electricity is your enemy.
Use as many screws as possible to attach the PS to your case; most use four. Ensure that the selector switch is in the proper position (“110” for U.S. power) and that the power is turned off. Cycle the power switch once, and make sure it’s in the OFF position.
Examine your molex (plastic four-pin) connectors and refer to the diagrams you drew in step (0) above. Use cable ties or rubber bands to pull the unwanted wires out of the way. This takes care of HDDs, CD/DVD drives, and floppies, and possibly even fans.
When you’re sure the molex connectors are in the right place, attach your motherboard power cord. As before, this should be foolproof, but make sure the ground pins line up and the “key” is in the right direction. At this step, I usually power-cycle the supply again (with no cord) to make sure all of my components share a grounding and that all the capacitors are discharged.
Go find that power cord. Attach it and power on the machine. If it works, you did everything right.
This is a complete and utter waste of time. Each 3.5" or 5.25" drive power connector has two black wires, in the middle. One is the ground for the +12V line (Red) and the other is the ground for the +5 V (Yellow).
Before you order a new power supply, look at your HP power supply and look at the combined power for the +3.3V and +5V rails. A larger number is better. Generally HP and Dell power supplies are built well and are conservatively rated. Your HP 250W supply may have similar power on these rails as a 350W supply. An Enermax 350W has combined 185W on those two rails and the Enermax is considered a quality power supply. If your supply has close to 185W on these two rails, you shouldn’t need to buy another one.
Hmm…interesting point.
Since ATI recommends a larger PS (I figure ATI has considered the types of computers their products are likely to be used in), and they’re not terribly expensive, I’ll probably spring for a new one anyway - just to be on the safe side. Antec has a 430W that looks appropriate…do you think this is going way overboard?
Thanks for everyone’s help. So that you know, I’m not a stranger to mucking about with stuff like this, and I’m quite cautious about wiring…I’ve just never had a need to replace a PS before.
You can’t really go overboard with PS wattage. It nmay be more than you need, but it won’t hurt the computer any, since it will only draw what power it actually requires. It comes down to 1) meeting the minimum requirements of your system, and 2) how much you’re willing to spend. If the 430 W unit is within your budget, go for it.
Yes, it’s a waste of time… Just about every connection to the power supply is “keyed” so that it can only be inserted one way. For example, hard drives and optical drives like CD and DVD drives have molex connectors that are rectangular on their edges, but rounded on the top. You simply cannot plug it in backwars without shaving off some of the plastic on the connector. Power connections for floppy drives look substantially different, but typically can only be inserted one way. And while I suppose the connector to the motherboard could be connected backwards, there’s a ridge on it that makes it painfully obvious which way it goes.
Standard ATX power supplies use 4 screws. Just four. Note that while the screw holes are placed roughly in the corners of the PS, the top two are off center. This is also so the PS will only go into the PC one way.
Lastly, as Q.E.D. says, it doesn’t really matter how “big” your PS is - your computer will only pull the power it needs. You could put a 500w or even a 750w PS in your box and be OK (although it would be a silly waste of money to do so).
As long as you’re going through the effort, go for a 350 watt (or more) PS - you won’t regret spending ten bucks more on this item. A cheap PS will cause you so much grief - random blue screens, shutdowns and other oddities. Better-quality units will also have more cables and connectors - a cheapie may have only two drive power cables, forcing you to use “Y” splitters, and some of the newer video boards need not just one, but TWO drive power connections, in addition to whatever power it’s sucking out of the AGP bus.
From personal experience, I can’t recomment PC Power & Cooling enough. Their Silencer power supplies and fans are amazingly quiet.
Regarding the plugs and what side ground is on (or isn’t) - Just pay attention to what you’re doing. If it feels like you’re forcing something, you are. Watch what side the bevels are on the larger drive plugs or which side the slot/tab are on with the small ones.
Yeah, PC Power & Cooling power supplies are the Mercedes Benz of the PC power market. Just like a Mercedes, you will pay for the privlidge though. Canot say enought good things about them though - they’ve been powering my dual Celly box for six years now with no worries. Antec are also very good as well.
Note that buying too large of a PS is not considered “Green.” Modern switching PSes waste quite a bit of power. An article I read the other day (paper, no link) said that about 30% of the power in a PS is wasted. The % waste goes up as the PS gets larger compared to the draw on it.
So there’s a tech committee to set standards and such for “Green” PSes. They’ll be along in a few years.
Also note that larger PSes have bigger or more fans. That’s extra power waste there as well as extra noise.
Basically, I wouldn’t go more than 50W above my max. predicted long term draw. (As I calculate it, not nec. the same as what a video card “total wattage” asks for.)
Computers use switching regulators, which don’t regulate well unless they have a minimum of about 10 to 20 percent load. If you have a system that doesn’t draw very much current and a really large power supply, you may find that your power supply doesn’t work properly.
Fortunately, with CPU’s drawing as much current as they do these days, it’s hard to actually set up a system that would fail this way. One way to fairly easily do it is get yourself a rather large power supply and one of those low power processor boards (commonly used in server farms since they generate a lot less heat than a regular motherboard).
Per the note by another poster unless, you are feeding 4 hard drives and 2 CDs in addition to the video card it is highly unlikely you will really need to upgrade your PS for this video card if there is only a 50 watt differential between the recommended spec and the current output. Do it if you want, but it is not likely to be “necessary”.
Yes, and no. It’s true that switchers have this limitation without additional circuitry to provide the required minimum load for stable operation, however, computer PSUs almost always have this sort of active load circuitry designed in.