Do I Need A Bigger PSU?!

[cmp2993]

I currently have a 250 watt PSU. This is the PSU that came with my computer. I bought this graphics card that recommends 300 watt or greater PSU but haven't ever upgraded it because things SEEM to run ok. I took a look at Speed Fan and saw that the volatge on my 12 volt rail seems to be what some may call a problem. What do you guys think, is there anything wrong with the voltages shown on Speed Fan?

Here's the link to the screenshot of Speed Fan with my voltages (photo bucket): http://i1013.photobucket.com/albums/af258/cmp2993/PSU.jpg

Please let me know. I have a 300 watt PSU I recently took from an old computer. So I could change it out I think with this bigger one if it's needed. Thanks for your replies!

-Chris


EDIT: The specs on my computer are located here: http://h10032.www1.hp.com/ctg/Manual/bph08793.pdf
My graphics card is an ATI Sapphire Radeon HD 3650 AGP 8X 512MB DDR2

 

[UniqueName]

Voltage goes down under load. Speedfan is probably wrong.

 

[rolli59]

You should be fine with the 250 watt but if the 300watt has more amps available on the +12 volt rail I would stick it in.

 

[shovenose]

speedfan sucks at reading voltages. its usually way off.
take a digital multimeter, open the pc case, and probe the 12v voltage on one of the molex connectors.

what brand is the 300w psu?

 

[cmp2993]

The 300w PSU is from a VERY old computer. It's a AGI. My current PSU is a 250w made by HIPRO.

 

[rolli59]

The 300w PSU is from a VERY old computer. It's a AGI. My current PSU is a 250w made by HIPRO.

Does the old one have the 4 pin CPU power (p4 connection)?

 

[cmp2993]

The AGI (I can't find ANY information on this company...it's like it doesn't exist!) has the 4 pin CPU, but my computer doesn't even use it. It just hangs there haha. This PSU also has the 20 pin motherboard thingy (technical, I know), that square 4-pin one to make it a 24-pin if needed, 2 4 pin molex connectors on same wire, another wire with 2 4-pin molex connectors and also a floppy drive or graphics card power connector, anotherrrr wire with a single 4-pin molex and the floppy drive/ graphics card connector, and finally a weird 6-pin flat looking cord which my computer doesn't use (I think only super old computers used it).

Get all that? xD

 

[rolli59]

Which one has more amps on the +12 volts? That is where the card needs the power from.

 

[cmp2993]

I have no idea how to figure that out haha. Wait, does the +12 volts correspond to a certain set of wires or something, I was always wondering this. Like people talk about a +/-12 volt rail, does that mean that one set of wires is a +12 volt rail and another is a -12 volt rail? xD

Anyhowww, how would I find out which has more amps on the +12 volts??

 

[rolli59]

It is usually printed on the sticker on the PSU somewhere!

 

[cmp2993]

My current PSU says on the sticker +12v = /14A. The 300w PSU says +12v = 15A.

So is there a wrong way to plug in a new PSU? Like if you need to plug in a 4-pin molex to something, does it matter which set of wires it comes from, or does it not matter?

 

[UniqueName]

Your HP is so old. I wouldn't touch it and especially if it's to swap a 7 year old PSU for an even older one. As long as your system works, great. When it stops, time for a new one. Hope you make backups.

 

[shovenose]

any 4pin molex will do with any device

 

[cmp2993]

Your HP is so old. I wouldn't touch it and especially if it's to swap a 7 year old PSU for an even older one. As long as your system works great. When it stops, time for a new one. Hope you make backups.

True, but the computer I took this 300w PSU from crashed right when the lady custom built it haha so it hasn't been used in a longggg time. So it hasn't had much of a life xD In comparision to my 7 year old (and still running) PSU it's probably a better trade.

The only reason I want to change it out is because I feel like I'm depriving my graphics card of power haha. I have this old PC upgraded to the max that is possible with it, and I run high graphic intesive games with it so I don't want to risk breaking my graphics card or losing performace because there's not enough power.

 

[rolli59]

My current PSU says on the sticker +12v = /14A. The 300w PSU says +12v = 15A.

So is there a wrong way to plug in a new PSU? Like if you need to plug in a 4-pin molex to something, does it matter which set of wires it comes from, or does it not matter?

That is not enough difference to bother replacing the PSU. If you start noticing instability then you would get extra 12watts from the 300watts where it counts.

 

[cmp2993]

That is not enough difference to bother replacing the PSU.

Hmm, well I want to to be sure everything is getting enough power. Is there a better way to check, since Speed Fan is bad you guys said lol.

 

[rolli59]

Well you could measure the 12 and 5 volts with a multimeter in an extra molex! The first thing you will notice if not enough power is sudden freezes or shutdowns!

 

[cmp2993]

Well you could measure the 12 and 5 volts with a multimeter in an extra molex! The first thing you will notice if not enough power is sudden freezes or shutdowns!

Well that's good at least I never get sudden shutdowns or freezes xD.

And ok so my moms boyfriend is an electrition and has one of those fancy volt meters. There's a red and a black probe type thing does it matter where you stick them in the extra molex connector? And my computer should stay turned on right? haha

 

[rolli59]

Set the meter to DC volts and the wires go as this black goes to a black wire (ground) the red goes to red (5volt) or yellow (12volt) respectively.

 

[cmp2993]

I unplug everything from the computer for this right??

 

[rolli59]

No need to you have to have it running, only way you get a reading!

 

[cmp2993]

Ohhhh, haha... well I just found that out with the help of Google. I found a detailed guide here just in case others come looking! ( http://www.devhardware.com/forums/power-supply-units-98/what-s-a-multimeter-how-to-use-it-to-test-75111.html ). I'm waiting for moms bf to get home so I can take his meter and test it... I'll post the results after I test it.

 

[cmp2993]

Set the meter to DC volts and the wires go as this black goes to a black wire (ground) the red goes to red (5volt) or yellow (12volt) respectively.

Okay, so my graphics card is hooked up to one of those small 4 pin cables that used to be used for floppy drives back in the day. It goes from a 4 pin molex (from the PSU) and splits that to the 4 pin small thingy for my graphics card and also to an extra 4 pin molex in case you need it. I tested this on that extra 4 pin molex, which is all on the same wire as my hard drive and graphics card. Here's my readings:

12 Volt Test (Yellow and Black Wire)

System at Idle: 12.16 v
System at Load: 12.22 v (Team Fortress 2 & Counter Strike Source)

5 Volt Test (Red and Black Wire)

System at Idle: 5.03 v
System at Load: 5.01 v (Team Fortress 2 & Counter Strike Source)

Soooo, feedback! xD

 

[shovenose]

seems totally fine. not a thing so worry about.

 

[rolli59]

^+1 that is very good, nothing to worry about there.