Need 285w, options?

dune · 03-11-2006, 11:45 PM

For reasons I won't go into, I need at least 285 watts of power (from calculator) for my first car PC project. I've been going through these forums quite extensively, but want to confirm some of my assumptions and see what my options are.

As I understand it, DC-DC power supplies are the best option because they're more effecient and don't run into the noise issues that the inverters sufferer from. However, the biggest one I can find is only 220w.

Inverters seem to be my only option to get this much wattage. However, "noise" is practically guaranteed to happen even with a pure sine wave inverter and while it can be reduced, it cannot be completely eliminated.

If I'm not worried about cost, what's the best choice for my project? Please advise.

simvegas · 03-12-2006, 12:15 AM

Couldnt you run 2 DC-DC power supplies in parallel? Should that provide enough wattage and amps?

greenman100 · 03-12-2006, 12:22 AM

can't advise when you do crap like:

For reasons I won't go into,

dune · 03-12-2006, 12:40 AM

I didn't go into detail because I've already got the hardware I'm going to run and I don't believe there's too much PC for a car.

I'll look into the dual PS's but not sure what the caveats might be. I could put the drives (two SATA and DVD-rom) on a different power supply, but the motherboard, videocard, memory and USB devices would all have to be powered from the same PS. This alone is about 220-240w.

Here's what I'm working with:

Intel P4 D845GERG2 micro-ATX motherboard
P4 2.4ghz 533 FSB
nVidia GeForce FX 5700
2x 512mb DDR SDRAM
2x Seagate 7200.7 SATA hard-drives
Sound Blaster Live! (PCI)
Sony DVD-rom drive
BU-353 GPS receiver (USB)
Gyration RF Keyboard/mouse receiver (USB)
Logitech webcam (USB)

simvegas · 03-12-2006, 12:46 AM

Cant you actually splice the outputs from both PSU's into one cable? Or you could just use one to run all your drives like you said. I thought you could splice the 2 outputs into one and run straight to your mobo.

dune · 03-12-2006, 12:53 AM

Are you talking about the 20-pin ATX motherboard connector? I guess I could, but that's a lot of splicing. Would that actually work?

simvegas · 03-12-2006, 12:57 AM

In my head it works. I wouldnt try it with AC power scenario but DC power it should work. As long as eerything is in parallel. Dont try with a SDC/PSU integrated system. Run a separate SDC in another circuit.

dune · 03-12-2006, 01:02 AM

Can you elaborate a bit for us n00bs (me)? What would an example be of a SDC/PSU integrated power supply? Thanks.

simvegas · 03-12-2006, 01:05 AM

Like a PSU that has a built in shutdown controller that attaches to the MB power switch. Having 2 of these systems in parallel would be a headache i think.

dune · 03-12-2006, 01:12 AM

So I guess I'd need a manual switch to kill power to the PS's then if I can't use the shutdown controller?

kirbycope · 03-12-2006, 01:14 AM

inverter.
/thread

Goines · 03-12-2006, 01:21 AM

You could have the second power supply set to not use a startup/shutdown controller, and always be turned on. Then hook a relay up to the +12 rail of the first power supply to turn the second power supply on/off.

That way you really only have 1 startup/shutdown controller which can be used to turn both power supplies on at the same time, and keep all devices sequenced correctly.

Basically the second power supply would not be used for its atx connector (20-pin) or power switch lead, but just its device power feeds.

dune · 03-12-2006, 01:32 AM

I think I'm going to avoid the inverter although it might be easier. A friend had video noise problems running the LCD off direct DC and connecting the video signal to a PC that is powered off an inverter. Seems that it's best to have all components that connect to each other to either be powered from DC, or all powered through an inverter. Is this logic correct?

Goines - sounds like that will resolve the shutdown issue. However, I'm worried that the requirements on the 20-pin ATX connector alone will overload the PS. I guess 220w is as high as they go on a 12v input.

DarquePervert · 03-12-2006, 09:01 AM

Actually, 250w without all the bells and whistles if you go with a KeyPower.

Haystack · 03-15-2006, 01:19 PM

unless you are going with a really high resolution, there is no need for such a good video card. A cheaper (read crappier) video card would have the same perfomance at say 800X600 with 256 colors as yours would at a higher resolution.

How big is the screen? if it is small, then you are just going to end up with a tiny desktop that you cant see. but playing quake 4 in the car wouldn't be out of question.

Then there is a full sized desktop power supply, that uses 300w, 12V input.
http://www.powerstream.com/dc2.htm

It only gives 1 to 5% regulation though. Would prolly still work without any real problems.