Power supply question.
 

I've decided to get a new case, as my current mid tower is getting cramped.

I've decided on an Aopen HX08, and it comes with a reasonably decent 300 watt power supply.

I'll be replacing it with my topower 420, but i'd like to be able to run dual power supplies. The topower to run the pc components, the aopen ps to run fans, lights etc.

I have no doubt that the topower will be able to handle it all on its own, but i'd like to be able to switch fans, lights etc on and off while the pc is running, and im worried about the power spiking when this happens.

At the moment i have to plan ahead what i'll be doing with my pc, and switch the fans on before i start it up. If i then decide that i want to switch them off i have to shut down, turn them off and restart....Kinda annoying.

The case has space to mount another power supply above the standard one, but i need to know how to switch on a power supply without having it plugged into the motherboard, so i can turn it on when i need to run the fans and stuff, then switch it off when theyre not needed.

Anyone got any ideas??

i never have problems with spikes when i open or close a circuit... (fans, leds, lights, stobes, etc)

I probably would be ok running them off one power supply, but after the power problems i've had recently im paranoid.

what problems? drop outs? get UPS... got 500VA for $25

I've had two power supplies (one 250 and one 300) die since i installed a geforce4 ti4400. They draw some current. I havent had any problems with my current one, but im cautious about turning fans on and off while its running.

Basically i figure that there would be no reason i couldnt just go nuts with everything being able to be switched on when needed if i had a second ps installed. Mounting it wont be difficult, i just need to know which wires to hook up to a switch so i can turn it on.

A UPS should ensure that current is regulated.

(btw, I think that case is major overkill)

I have a surge arrestor and circuit breaker, but switching something on and off would cause a slight spike in the power supply if its running. That spike could then be transferred to the rest of the system. While it might not hurt anything, with the problems i've had with it recently im not going to take chances.

The case is overkill. But big cases are good for warm pc's. And i do have a reason for wanting a full tower. With my current case i cant use the bottom 5 1/4 bay, as there is a capacitor on the motherboard which gets in the way, and the top 5 1/4 inch bay is unusable, as there are fans that get in the way, making it impossible to fit a drive in there. That leaves 2 bays. The bottom 2 bays are taken up by a 80mm fan, leaving one 5 1/4 inch bay left, which is used for my cdrw. Not good if i want to add a dvdrom or dvd burner or anything similar else in the future.

Like I said, a UPS should fix that problem. When there is a surge in power, the UPS reverts to battery power, ensuring that current is consistent. I know what you mean about spikes... turning on my PC in my room makes my lights dim for a fraction of a second. My friend's office computer is hooked up to a UPS, but the effect of a spike is significantly minimized (it's in an office, but it still uses incandescent lighting, like in my room).

as for overkill... well, it's not a bad thing... just overkill :D Because you have large open areas in your case which can create backwash, ensure that you direct airflow so that hot air isn't just being recirculated. Plexiglass ducting is great for this.

Im not worried about external spikes, im worried about an internal spike within the power supply...A ups wouldnt help that.

As for the airflow issue, i've already planned how it will be set up.

Basically, that case is split into two sections, the top (housing the 5 1/4 bays, and the bottom (housing the motherboard and 3 1/2 bays). I'll be putting an 80mm fan in between those sections to keep the airflow in the case moving. 4 120mm intake fans (two on the front bezel, two in the side, all thermostatically controlled, running between 1000-2500rpm will make sure a lot of cool air is being brought into the cases lower section. The topower has dual fans (thermostatically controlled), so it will draw warm air rising from the cpu heatsink, as well as dual 80mm fans at the rear of the case near the cpu. That should be plenty of airflow around the motherboard.

The top section will have two 60mm fans in a custom hard drive cooler drawing air in from the front. And two 80mm fans drawing air out the top. Also the aopen ps will help to draw some warm air out the back of the case. If its needed i may add another 120mm intake fan for the top, section, but i dont think it would be necessary.

If the air inside the case is less than 20 degrees then no case fans will be running, 30 degrees theyre all running at minimim speed, 40 degrees + theyre running at max. So if i decide to leave it running 24/7, there will be times that the fans switch on by themselves.

So when its just sitting there doing nothing it will be quiter than the average pc, but the cooling system will have enough headroom for hot days and intensive gaming sessions.

As you can see i've thought this out, but i just need to know how to wire the second power supply.

I regularly plug and unplug my 120mm fan and 80mm ones when the computer is running with no problems at all. You shouldnt have any either and my system is pretty packed with drives and PCI cards etc. Or alternativly you can get drive bays that you plug fans etc into that have pops on the front so you can adjust the speed or just switch em off really easily.



Having a big case is also not always a good idea for cooling. Having an 80mm intake fan in a case that size wont do anything in the parts where the motherboard and cpu are. You just end up with big areas in the csae where no air moves, very bad for cooling. But you might be using Delta focused flow screamers that shift 66cfm, i dunno.

edit: I didn't read your post above

Along the same line of thought, couldn't you use a rheostat to slowly decrease/increase power to the fans, thereby eliminating the threat of a spike?

Typo on Phily's part I think rm'
Should have read 'pots' - same thing as a rheostat.

UJ

yup /me bad :cry:

use rheostats to control the fan speed... you can do that..., but to turn on the power to the ATX you have to short the Power lead to the ground and i think that does the trick... but try it on one you DONT need just in case im wrong. fyi read signature... IT APPLIES HERE!

i have a power supply problem too

my laptop is shit and my power supply port kinda works but now it usually doesnt.

n505ve. if some one can find a premanant fix to my laptops power problems i will pay for your services.

sledge hammer :D

this should be the offical power supply thread..or sumptin :igor:

I think i need a new power supply..when I try to multitask while watching tv on my puter my computer just turns off and on again.

Sounds like it could be a bad stick of ram or a driver issue cmw. Youre running winxp right??

Well xp will automatically restart instead of showing a blue screen by default. Just go into control panel > system > advanced tab > startup and recovery settings > untick automatically restart.

Then when it crashes it will show you what the cause of the problem is.

My ram is new, new drivers, and im running win2k...it happened on win98, 2k, and xp and I can hear the harddrive loose its power

It has to be a hardware conflict with drivers.

Take out all the hardware you dont need to run your computer. run it and test the hardware in your machine.

Add a removed peice of hardware. test it.
Repeat for all peices of hardware :(

Thats how i figured out my cheap shitty Nic was causing my laptop to crash :) I thought it was my laptops new RAM. Bad drivers make computers restart for no reason.

Not usually. Theyre more likely to cause a bsod than a hard reset.

CMW: Try disabling all power options in the bios and in windows. Failing that, try a new power supply. Anything over 350 watt and is made by a reputable manufacturer should be fine. If that doesnt help then remove as much gear as possible. Try running it with just the motherboard, cpu, ram and one hard drive. If it runs fine like that then its most likely either a hardware problem with one of your cards/drives.

try moving the cards to different slots... like free up the 1st PCI under the AGP and the 3rd as well...

would overheating cause random restarts? sometimes my bsod come after the random restarts :(

Its possible that heat may be causing it whiteflip. I know my mobo has a function that shuts down the puter if the cpu reaches a certain temp. I have it set to 70 degrees celsius, so if the cpu fan fails, it will just power off before any damage is done. But i dont think something like that would cause a random restart.

Heat is a common cause for full system hangs and bsod's however.

If it still happens with a good power supply, all cards (except video) and uneccesary drives removed, a fresh install of windows and all covers off the case with a house fan blowing air in then its safe to assume its a problem with the video card, motherboard, cpu or ram. Then its time to start swapping components with hardware thats known to be in good working order.

Back to the original topic, i finally found out how to get a power supply to turn on without having it connected to a motherboard.

Unfortunately, that means that it will need an on/off switch (not momentary) so it can be turned on and off.

But i've already thought of a way to get around that. I'll use a 12 volt relay, hooked up to one of the main power supplies molex connectors, so the second ps switches on when the first one does, and i'll also fit an on/off switch inline so it can be turned off seperately.

While browsing through a catalogue from an electronics store here in aus i found they sell these 12v motor controllers/car headlight dimmers. Theyre rated up to 20 amps (240 watts) so should easily handle a dozen or so fans running off it. Less messy than just using rheostats too. They also sell these dual probe digital thermometers (which would look uber cool if ripped apart and custom fitted into a drive bay cover) with a built in alarm that goes off at a certain temp. I figure i could just find the circuit that triggers the alarm, and run that to the motor controller, so at say when the air temp reaches 30 degress inside the case, the fans switch on.

Would be kinda cool....if it works..:igor:

The pci slot under the agp slot is empty. And i think I need a bigger power suply cause I have a 64mb graphix card, 2 fans, a nic, a tv card and probably more leeching of that psu