...Which forum to post this in, so I chose this one.

I'm curious whether or not I should get a new power supply. Right now I have a 300 Watt Enlight, it works fine for what I have right now. But I'm thinking of adding stuff...and I want to know if it will have enough power to do what I'm wanting.

Right now my specs are:
1.4 T-bird
FIC ad11
256mb Kingston ddr
IBM 40 gig 7200 RPM
LG DVD
LG CDRW
4 80mm Fans, connected to a Rheobus
GeForce 2 Pro (Going to update to a GeForce 4 ti4200 128 mb)
D-link NIC
Modem
Floppy Drive
XP Pro
-----

I want to add another harddrive (80 Gigabye, 5400 or 7200), and I'm updating the video card. I'm also getting new fans, they are going to have LED's in them, I'm not sure if they will take any more power, but... I also want to add a homemade LCD screen to the case. (this take a 5v power source because or backlight)

So do you guys think I will be able to run all this with my 300 watts? I know it would be pushing it, but do you think it's pushing too far?

Any help appreciated,

Camper

Add up only the components below that your system has to determine wattage:

AGP video card - 35-50W
PCI video card - 35W
AMD Athlon 900MHz-1.3GHz - 50W-65W
AMD Athlon XP 1.47MHz-1.73GHz - 60-75W
AMD Duron 1.0MHz-1.3GHz - 50W
Intel Pentium III 800MHz-1.4GHz - 40W-55W
Intel Pentium 4 1.4GHz-2.0GHz - 65W-85W
Intel Pentium 4 Northwood 1.6GHz-2.0GHz - 60W-75W
Intel Pentium 4 Northwood 2.2GHz-2.53GHz - 80W-90W
Intel Celeron 1.0GHz-1.1GHz - 35W
Intel Celeron 1.2GHz-1.8GHz - 45W-65W
ATX Motherboard - 40W-65W
128MB RAM - 10W
256MB RAM - 20W
24X or higher IDE CD-RW Drive - 35W
32X or higher IDE CD-ROM Drive - 25W
10x or higher IDE DVD-ROM Drive - 20W
SCSI CD-RW Drive - 17W
SCSI CD-ROM Drive - 12W
5,400RPM IDE Hard Drive - 13W
7,200RPM IDE Hard Drive - 18W
7,200RPM SCSI Hard Drive - 24W
10,000RPM SCSI Hard Drive - 30W
15,000RPM SCSI Hard Drive - 45W
Floppy Drive - 5W
Network Card - 4W
Modem - 5W
Sound Card - 5W
SCSI Controller Card - 20W
Firewire/USB 2.0 Controller Card - 40W
Case Fan - 3W
CPU Fan - 3W

The wattage numbers above are estimates and may be rounded to the nearest 5 watts. The given wattage may only reach the specified level during power-up or during peak usage. Always purchase a power supply with a bit more wattage than you calculate you'll need, to make room for future upgrades.
PS Dont forget anything

Also 256MB is not enough for XP! 512 minimum. XP runs 170MB at idle. Running 4 windows and Winamp3 I use 251MB.
If you Game at all you can hit over 400MB easy.
Do yourself a favor and get some more

Yeah, I knew about the ram thing, I just was pretending it wasn't a problem. So it looks like I would probably be pushing it, if not going over the limit..I don't know what I should do.

Camper

Now come on, you know what to do. You just don't want to do it. I mean this in the nicest way possible. The only time we say that is when we don't want to spend the money.

This is only friendly advice, if $$ is an issue, as it is with me at the moment, get the mem first and then go up with the powersupply.

No! No! No!

Here's a simple equation to use:

Watts consumed = Voltage times Current

You have a 300 watt power supply, and it's plugged into the wall which supplies 120VAC. Therefore you have 2.5 amps (300 / 120 = 2.5) to work with. Of course, most power supplies are only about 80% efficient, so you really have about 2 amps. Is that enough?

The easiest and definitive way to find out is to hook up an ammeter inline with the power cable. I did this with my biggest box, with the following specs:

2xPIII 1.0 GHz Processors
1024MB PC133
Geforce 256
2x80GB Storage drives, 1x40GB Boot Drive

The most current draw I got was 1.1amps.

Don't worry about adding another power supply. The easiest way to tell is by adding the second hard drive and seeing if you begin to notice instability problems.

Wixx, 300W = 2 Amps? Sorry, but you missed that one. Which line are you talking about? My old Enermax was 300W but had 14 Amps on the +12. My current Antec 430 runs 20A off the 12V.

I know this from my experiments with TECs. 2 Amps would barely power up a computer.

no no you need the pc power and cooling inc. dule redundant 700 watt redundant power supply and the APC serverfarm back up 20kwh battery back up. then outside you should get a cummins 30kwh disiel back up generator. all your wireing should be replaced with 2 gauge oxygen free copper braided wire with audiophile silicone insulation.

*Smacks carbongraphite*

Camper

bigakita, you're mixing DC and AC numbers around when you shouldn't.

It's like this:

EI = P
120VAC * 2.5 amps = 300 watts.

Computer power supplies work by first converting the main 120VAC into something workable--first with a transformer to knock the voltage down, then some capacitors to filter power supply noise, and then a rectifier to convert to DC. Usually you get 5VDC, but sometimes 12VDC. Depends on the manufacturer.

The 5VDC is then converted to other voltages. This usually goes through a series of linear voltage regulators to generate +12 and +3.3, and then an inverter to get -5 and -12. Voltage regulators are basically transistor amplifiers, so they get very hot and require a bigger heatsink. Power supplies with high ratings use higher-quality parts in this process as well as bigger heatsinks.

The point here is that your computer's power consumption is what it draws in DC, plus the energy wasted in the AC-to-DC conversion (in the form of heat). Assuming none of your components exceed the DC specification, and the total consumption doesn't exceed the AC specification, you're alright.

One final note is that a lot of manufacturer's use bull**** specifications on their PSU's anyway. Your Enermax might have very well been able to deliver 14 amps at 12VDC, but since the 12VDC was probably derived from 5VDC, those figures don't include any kind of load on the +5 or +3.3 output. As soon as you hook up a motherboard and a drive that requires those voltages you find your maximum output on the +12V drops dramatically.

Okay, it's like this:

Motherboard: 65 Watts (.54 Amps)
Proc: 75 Watts (.62 Amps)
DDR 256: 20 Watts (.16 Amps)
DVD: 20 (.16)
CDRW: 25 (.21)
GF2: 50 Watts (.41)
Nic: 5 (.04)
Modem: 5 (.04)
Floppy: 5 (.04)
7200 RPM HDD: 18 Watts (.15)

TOTAL WATTAGE: 268
TOTAL AMPERAGE: 2.37

That's without totalling active cooling or anythin' else extra. Admittingly I aimed high on some components, but it's pushin' close to 300. Ram should be okay though... at it'll only take it up to roughly 278 Watts.

Wixx, I think you may have over-complicated... but you're right, the RAM shouldn't be a big deal. I think those wattage ratings are at the highest level of output... which is probably why your dual proc rig didn't spike out higher.

Anyway... my two cents on a lazy Sunday evening (like it matters when you're unemployed) ;-)

Wixx, I know that my 430 PSU has a steady 20A off the 12V line, tested. I also know that my 250V PSU is running 3 120mm and 2 80mm Fans, 4 lights, 2 CD's, 3 hard drives, 4 hard drive cooling fans, a NewQ, floppy, LS120, a baybus, and a rheobus, and still has overhead. I think your methodology is underating capabilities.

OK then,

How many watts do you folks think I should be looking for? I was thinking around 400, or 430. Do you think that would be enough?

I was thinking 430 because I'm not sure how much light LED fans put out, so I might need to get a CC. I'm trying to get away with just the LED fans, because I don't want an unsightly piece of tape or screws going through the bottom or sides of my (plexiglass) case.

I also have another problem wth my current PS. It sags..sort of. From the back, where it's mounted, to the front, it leans down. I figured out that it's the actual power supply's frame that's loose, and it's causing it to lean down. Any ideas? I've tried putting washers behind the bottom holes, but all that really does is put a gap between the bottom of the PS and the case.

Happy Camper