Helping people with computers... one answer at a time.

Replacing a power supply is reasonable common solution to some problems. Making sure you have the right wattage power supply is important. And bigger doesn't hurt.

I want to upgrade my current case that has a 300W PSU to a nicer looking case, but it has a 520W PSU. Is it ok and how does the "W" difference influence PC operation?

It's quite all right, and if things were working well before, you probably won't notice a difference.

There, now that I've answered the question, let's look at why, and just what that "W" means. I get questions on this topic frequently.

The "W" stands for "Watts", which is a measure of electrical power. A power supply with a higher wattage rating is capable of delivering more power to your computer.

That's more electrical power. It won't make your computer run any faster or give your more "computational" power - this is simply about electricity.

A new power supply is typically called for in one of two situations:

  • Your existing power supply is failing. Either it has failed completely or it's "slowly" failing and no longer able to produce the power your computer requires. As it fails, unexplained crashes usually become more frequent.

  • You've added hardware in the form of add-in boards, memory expansions, additional hard drives, or other devices that draw power from your computer, and you've exceeded the previous power supply's capacity. This, too, can behave like a failing power supply.

In either case, the solution is a replacement power supply. In the first case, a power supply with the same rating as your old one will do; in the second case, you'll need one with higher wattage.

I typically recommend replacing with a higher wattage supply, anyway, since it harms nothing to do so.

"It's better to have too much power than too little."

I've heard a concern that a high-wattage power supply can somehow "force" the power onto the computer, causing overheating and burnout. Nothing could be further from the truth. A power supply supplies power in response to need; it doesn't push power anywhere. If your computer only needs 100 watts, then a 500 watt power supply will only supply 100 watts. Why have a 500 watt power supply? For "peak" usage (sometimes hardware will require sudden "bursts" of power, such as at start up or under high load) and for future expansion.

It's better to have too much power than too little.

Two important aspects of power supplies:

Get the right size. By this I mean physical size -- there are several standard sizes out there, and they are not interchangeable.

Make sure the machine is well ventilated. A higher capacity power supply will run warmer, particularly if it's providing more power. Make sure that its fan and any additional fans in your machine are working properly and that the airflow path is unobstructed. Overheating due to blocked airflow is perhaps the most common cause of PC equipment failure.

Oh, and if you have a laptop - you're out of luck. Laptops come with the batteries and power supplies that they come with. There's no real way to "upgrade" their power capacity.

Article C2873 - December 17, 2006

Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

Recent Comments
15 Comments

so if my computer has a 300 watt power supply and i put in a new 750 watt, it will over heat.

Is that a question? It's unlikely. It depends on the computer, the power supply, what other hardware is in the computer, the venting and how you use the computer.
Leo
29-Nov-2009

Posted by: LOU at November 28, 2009 10:59 PM

I have to disagree with the statements regarding to big of a PSU. The components use what they want from your PSU, it doesn't force more in. The PSU isn't "Burning off the extra" it simply has the capability to perform at higher wattage's if needed, yet will only supply what your components want. They want 200watts then the PSU provides 200 watts, got a honkin grafix card that means you need 400watts you get 400watts. If you have an 800watt PSU it doesn't sit there with 800watts of potential energy stored in it dissipating the extra in the form of heat. It only means it has the capacity to do 800watts.

I've been running a 750watt AERO PSU in the same rig for going on 8 years with no issues caused by the PSU. I had one motherboard that fried a capacitor and later found it to be a design flaw in the IC7 from ABIT (thank god they are gone!), so to remedy I installed the IC7 Max3 which has a fan and ducting over the capacitors. I also originally had a EVGA FX5700LE card and changed it to the EVGA 7800GS which required a 4pin molex so I was glad I had installed the 750watt supply. Now my son has this computer and I see no reason it shouldn't last another few years for him, I just inspected everything and it looks great. It's now running WIN 7 Pro and has a Autobot Bumblebee theme to the case and the system.

My new rig is running a Kingwin 1220Watt in it, staying cool too. Great product by the way!

You want to upgrade your PC's in the future buy good parts first, don't scrimp on some cheap brand, just go find a good deal on a good brand. Next time don't buy a pre-built PC if you want gaming, get one built or build it yourself with the right stuff to game! You waste more time, money, and effort with upgrading a Name brand PC to do something the manufacturer never intended it to do.

Posted by: Werewolf at January 9, 2010 3:14 AM

This is what I was looking for, a clear, concise answers to my questions about power supplies.

Posted by: saint4God at November 9, 2010 10:38 AM

Danke! I'm not new to computers or building them, at all, but there are some things I never got around to learning everything about; power supply units are a good example of such a thing.

I came here, because I have recently ordered a state-of-the-art gaming rig, since I can't be bothered to build one. I have concerns about whether the PSU will be safe and reliable, as it is a Dutch make and put in a computer that will be shipped from Germany, via Amazon, for over £400, although it's worth easily over £800!

The PSU I'm concerned about, is the "Techsolo STP-650" that, according to at least 2 sources online, is indeed certified (CE) but I need to KNOW, for sure, first, otherwise I will have to just fork out for a Corsair. Any advice, please share!

Viel glück mit ihre Computer, leute!

Posted by: Der Teufel Mann at December 8, 2011 4:42 AM

Agree with your answer. on high memory machines, the power supply may be just adequate and thus a slow machine. my example is the Asus CG1330 with a supplied 400 watt power supply for 8 Gig of memory. Must purchasers increase the power supply to a 600 watt and then have a machine worth speaking about. Increasing the memory to 16 Gig may require an increase in the power supply especially if one increases number of monitors.

Posted by: HHWieck at December 10, 2011 6:06 AM
Post a comment on "Is it safe to install a higher wattage power supply in my computer?":





Remember Me?

(You may use HTML tags for style)

Before commenting, please...

  • READ THE ARTICLE. A comment that shows you didn't will be deleted and ignored.

  • Comment only on the article. Use the search box at the top of the page if you have a question about something else.

  • NO PERSONAL INFORMATION in the comment. No email addresses. No phone numbers. No physical addresses.

  • Anything that looks the least bit like spam will be deleted. Links to unrelated sites or links that appear to be primarily promotional will be deleted, or the comment will be deleted.

  • Don't ask me to recover lost passwords or hacked accounts. I can't. Those comments will be deleted.

  • I can't respond to every comment. And I can't vouch for the accuracy of others who do.

Please wait. Your comment is being processed ...