Question about PSU's

[Movingshrub]

I swear trying to pick the right PSU requires an BS in electrical engineering. Anyways, I'd really appreciate if some people could advise me.
Currently, I'm running a Shuttle AN35-N Ultra with a 2500+ Barton (Not O/C atm)
Geforce 4 Ti 4200
3 sticks of ram. All PC2100. 2 256mb and 1 512mb
1 3com 905tx 10/100 NIC
1 SB Live 5.1
3 7,200 rpm hard drives
1 CD-RW Optical Drive
3 Case Fans that push around 20cfm each
1 Cpu fan that pushes around 60cfm
Antec 300w PSU which I believe produces 20A on the +3.3, 30A on the +5 and 15A on the +12

Whenever I hook up the 3rd harddrive the machine gets very cranky. If I try to turn it on, I can hear each drive spin up individually, and I'll get random BSOD, and also have problems when just trying to start the machine. Quite often it wouldn't turn on.
After disconnecting the HD, it would work much more frequently. I attempted to add up the usage of my machine'stTotal wattage and the demand on each rail. I wasn't able to find the power values for the motherboard or the video card, so these are the educated approximates I was able to come up with.
6A +3.3V
14.88A +5V
15.35A +12V

Also, at the time of this I was monitoring my voltages using "Hardware Sensors Monitor" This is the lowest of each rail since my machine has been on for the past 20 minutes. +12 (11.52) +5 (4.73) I/O +3.20 Ironically I also tried using a multimeter and would get results very close to the spec of the rail, so which to trust...?

So according to all of this, my machine would hit the cap only if it's using the max wattage for all devices at once.
That adds up to 278W which is the max output of my PSU. So I wouldn't think I'd be having a problem, but for peace of mind, I'm going to upgrade my PSU. I was looking at the Antec true power 480($83), ( +3.3 30A, +5 38A, and +12 22A combined max of 460W) and the Antec true power 550 ($110) (+3.3 32A, +5 40A, and +12 24A combined max of 530W) They both seem pretty good PSU, but lacking in the +12 rail. So finally I turned to a Enermax EG465 460W Psu ($86). It produces +3.3V 35A, +5V 35A, and +13 33A with a combined 200w for the +3.3 and +5, and 460W for all rails +3.3 ,+5, +12, -5, -12, and +5Vsb.

I tried using the power supply calculator here. http://www.jscustompcs.com/power_supply/
It kind of took away my faith though when it assumes you start out with a demand of 36W then click a box to add a hard drive (25W) Well..last time I checked 36+25 = 61, not the 68 the calculator returns. Quite a few of the product would add more then was listed in the parenthesis. Unless of course power usage doesn't follow a straight curve..otherwise that calc seems screwed up to me.


How is some normal person suppose to know what to get? To me the Enermax looks like the best since it pushes the same amount of Wattage and has higher amperage on the +3.3 and +12 rail and only 3 less amps on the +5 rail. I'd really appreciate some input. I'm also purchasing in the event I was to upgrade in the near future. Thank you to any that respond.

Phil

 

[ZL1]

Antec True 430W
used one of these in a build I did for a friend (p4c 2.4@3.0, 512mb pc3200, asus p4p800, GF4 TI, two hdds, one dvd, one burner, 2 NICs, one SB, 3 fans)


D

 

[eno]

I run a Antec 430 as well. I really have not done alot of research like you did on power but I have used Antec PS on every build and haven't had a problem so far.

I have used Antec 303 (300watt)
330watt TruePower
350Watt SmartPower
430TruePower.

My system I am typing this on runs a 430w and it powering:

P4 3ghz OC 3.5ghz
Abit IS7 (950fsb)
HyperX PC4000 4x512mb
1 WD HD 120gig
9700pro OC 9800pro
6 High RPM 80mm fans
1 Tornado
Audigy2 LZ
3 CC lights
2 Optical drivers
Floppy.

It seems to run perfect. I have been asking about my -12v and -5 rails though they are really low, but from what 90% of people tell me, that the - rails do not matter for new systems. Hmm

Sorry not a real good answer to your question. Just get the most poweful your money can afford.

 

[Movingshrub]

See that's the issue, which one is "more powerful" ? That's what I'm trying to understand. I understand more wattage is typically better, but not always. There is a 450W ?AMD approved? Austin power supply that produces
28A +3.3V
30A +5V
15A +12V

and overall gives good wattage, but the +12 rail is lacking. Is there anyone who actually understands this enough to give more then a blind recommendation of what works based on past experience, and can comment based on technical understanding?

 

[ZL1]

Originally posted by: Movingshrub
See that's the issue, which one is "more powerful" ? That's what I'm trying to understand. I understand more wattage is typically better, but not always. There is a 450W ?AMD approved? Austin power supply that produces
28A +3.3V
30A +5V
15A +12V

and overall gives good wattage, but the +12 rail is lacking. Is there anyone who actually understands this enough to give more then a blind recommendation of what works based on past experience, and can comment based on technical understanding?

my recommandation was far from blind, I did lots of homework before going with the True430, but Im too lazy to write a 3 page post right now just like I was too tired to do it last night
a good review I read while doing my research http://www6.tomshardware.com/howto/20021021/index.html
it also has a table of how many amps go where and how many you might need


D

 

[Matthias99]

For three 7200RPM hard drives you'll want something with more than 15A on the +12V line if possible. The fact that you see instability with the third one means you're pushing it already.

The +3.3 and +5V lines power your motherboard, CPU, PCI/AGP boards, etc. It's pretty rare to see an issue on these with a newer power supply, unless you've got a CPU dissipating over 100W, a heavy-duty graphics card, and some power-hungry high-speed RAM.

The +12V line is used for a few things on your motherboard, but mostly it powers the motors in your IDE/SCSI devices. If your calculations show that you're going to be pulling around 15A on the +12 line, you want something rated for *more* than 15A. The biggest load you'll have here is on bootup (when it has to spin up all the drives) -- you won't usually be running I/O to all three drives (and the CDRW) at once.

The -12 and -5 lines are not used anymore, which is why the amperage ratings on them are so low. The new ATX power spec standard actually says that power supplies don't even need to have them. I suspect that within a year you'll stop seeing them on new PSUs.

For your system, I think even an Antec True330 would be fine -- you won't usually be using every single component at once, and that model has an 18A rating on the +12 line. The 430 is just a few bucks more and may be worth it for the extra security (it's rated for 20A on the +12 line). The cheaper Antecs are *not* as good as the TruePower/TrueControl line of supplies, so it doesn't surprise me too much that you're having problems with yours running it near its limits.

Other well-regarded brands are Sparkle and Fortron -- one of those might be a bit cheaper for the same specs. I have a quiet Seasonic that I really like, and I'm probably going to get one of their new "Super Silencer" models, which are both quiet and high-efficency (and sort of expensive). Stay away from PowerMax and Q-Power -- heard bad things about both.

The review in the above post is a good place to start. Just keep in mind that you'll probably never have a load over 300W in your system.