the ultimate "do i need a 24pin PSU ?" thread

[djmarkus]

Hi guys, i've ordered an msi neo sli with the sb sound onboard, a so939 3500+, and 1 fx6600gt i hope to buy another one and sli them when one 6600gt isn't enuf, i also ordered with them a 20pin thermaltake butterfly 480w which supplies 15a to the 12v rail, do yous guys think tis will be enuf? if not will someone recommend a psu? does anyone know any places to get good psu's cheap that will post to europe(ireland)?
cheers

 

[Algere]

Originally posted by: Creston
However, it's a PSU that came with the system, and I have no details on it. Is there any way of figuring out how much Amps it has, short of getting a multimeter and jabbing it into several areas and hoping it will give me a reading which I still won't know what it means?

Are there any type of markings on the PSU itself? Specs are usually listed on the side of a PSU.

Originally posted by: djmarkus
Hi guys, i've ordered an msi neo sli with the sb sound onboard, a so939 3500+, and 1 fx6600gt i hope to buy another one and sli them when one 6600gt isn't enuf, i also ordered with them a 20pin thermaltake butterfly 480w which supplies 15a to the 12v rail, do yous guys think tis will be enuf? if not will someone recommend a psu?

The processor (6-7A) & 6600 GT (PCIe 16X slot = up to 5.5A) can add up to a possible 12.5A load - albeit doubtful, excluding additional load from fans & drives. Also if that Thermaltake PSU is spec'd @ an operating temp of around 25C. It's possible you'll have less than 15A should the PSU output more than 25C of heat.

IMHO, I'd get a PSU with more juice & 24 pins as that PSU by the sound of those specs is aimed more towards the power needs of the early Athlon XP/P4 (Willamette) generation. Perhaps this can give you an idea of the amount of power you'll need.

 

[Creston]

amdskip in another thread helped me figure out what it was, thanks Algere

It actually has 34A on the 12V line, so it's more than plenty.

Creston

 

[Creston]

I need some advice.

I have a Gigabyte xxxx nForce 4 Ultra chipset mobo. It has a 24 pins connector on it, but Gigabyte taped over the last 4 pins, so my no name PSU (500W, 12v@34A) could connect its 20 pin connector to it fine.

I have an athlon 3500 90nm, 1 Sata DVD burner, 1 IDE dvd rom, 1 SATA HD, wireless pci network card, audigy 2 pci, Radeon X800XL PCI-E, Thermaltake cooler and 5 case fans in my system.

Looking at the ratings, I would say that 500W plus 34A on the 12V line should be plenty to run this system, right? And yet, I'm having serious stability issues, but absolutely 100% completely random.

I can run games for 6 or 8 hours without any problem at all, and yet at the same time, I'll reboot and run the same games, and they will crash within 15 minutes to 2 hours of playing. My crashes are always hard lockups, although sometimes VPU recover will be able to get the graphics card back.

I'm at a loss whether this is due to a dodgy PSU, or whether this is due to a flaw in my graphics card (my main likely culprit then would seem to be the memory chips on the 256MB card). But one day I think it's this, and the other I'll think it's that.

I ran Doom 3 at Ultra quality, to get those mass textures shoved into my card, and sure enough it crashed within 2 minutes.
But then I tried it again, and it ran fine at Ultra Quality for two whole levels.

In an effort to see if it was power related, I upped the voltages to my CPU by 0.025V and to my PCI-E bus by 0.1V, but that was enough to shut my system down completely, and I had to boot back into BIOS and reduce the voltages again. (And I'm scared to do it again for fear of the system not ever booting again...)

Since ATI is dragging their heels in coming up with any kind of response to my ticket with regards to testing the graphics card, I'll ask here in this thread.

Do you think that this could be power related? If so, what would you recommend would be a good ATX2.0 PS for use in this system? I'm just worried that my current PSU is not getting enough juice to my X800XL due to the fact that it has no molex connector on the card, and that I have no 24 pins connector...

Any advice greatly appreciated
Thanks in advance.

Creston

 

[evilangeltwins]

I will get one w/ 24-pin just to be safe, who knows what will happen in 2 yrs

 

[jim1976]

Well I finally went with the Neopower,which IMO was one of the best solutions for my rig. When dual cpus will be here and the specs will be well defined, then if necessary I will proceed to the purchase of a better one. For now I find Neopower an exceptional psu for the money I bought it. and the quality of it is unmatched.Best I've seen so far

 

[Promethply]

Really appreciate this very informative thread, Flexy, as it clarifies alot of fog I had when using an older 20 pin powersupply connected to a new motherboard with 24 pin.

 

[BeeBoy]

I've read the thread and its great i must say. i have asked a couple of people about whether i can use my motherboard with a 20pin connector and 1 guy said no way, another said sometimes, depending on the motherboard and another one said yes, sure.

So the reason i'm writing this is that i just got my computer today and i had a psu already which has a 20 pin connector. the PSU is a Q-Tec 550W.
The system i want to use it in looks like this:

Asus A8N SLI motherboard (has 24 pin connector)
AMD 64 3000+
1GB DDR RAM
XFX Geforce 6600GT Gamer Edition
200 GB Maxtor hdd
Pioneer DVD writer
Thermltake Xaser III ATX tower with 7 built in fans

Now, on the motherboard there is somethign called the EZ plug which is supposed to be an asus invention or something, that ensures stable power flow to the video cards and only requires a 4 pin power connector (i think thats what is called a molex)

So can i use this PSU with this motherboard using only the 20 pin connector or do i need a better PSU, or is it enough if i just buy a 20 to 24 pin converter?

My brother used this very same PSU in his computer (he upgraded the PSU to a vantec and gave me this one, because he bought an XFX Geforce 6800GT)
His setup looked as follows:

AMD Opteron 140
MSI K8T Master FAR2
2GB DDR RAM
Asus Geforce 2 gts
2 * 160 GB HDD
LG Dvd burner
Thermltake Xaser III ATX tower with 7 built in fans (same as the one i have also)

So he says he used this setup with the 20 pin power connector with no problem, but my concerns are about the fact that he didn't have a really good video card then, plus it wasn't a PCIe card either.

So i was wondering if you could help me.

 

[Algere]

Originally posted by: Creston
I need some advice.

I have a Gigabyte xxxx nForce 4 Ultra chipset mobo. It has a 24 pins connector on it, but Gigabyte taped over the last 4 pins, so my no name PSU (500W, 12v@34A) could connect its 20 pin connector to it fine.

I have an athlon 3500 90nm, 1 Sata DVD burner, 1 IDE dvd rom, 1 SATA HD, wireless pci network card, audigy 2 pci, Radeon X800XL PCI-E, Thermaltake cooler and 5 case fans in my system.

Looking at the ratings, I would say that 500W plus 34A on the 12V line should be plenty to run this system, right? And yet, I'm having serious stability issues, but absolutely 100% completely random.

I can run games for 6 or 8 hours without any problem at all, and yet at the same time, I'll reboot and run the same games, and they will crash within 15 minutes to 2 hours of playing. My crashes are always hard lockups, although sometimes VPU recover will be able to get the graphics card back.

I'm at a loss whether this is due to a dodgy PSU, or whether this is due to a flaw in my graphics card (my main likely culprit then would seem to be the memory chips on the 256MB card). But one day I think it's this, and the other I'll think it's that.

I ran Doom 3 at Ultra quality, to get those mass textures shoved into my card, and sure enough it crashed within 2 minutes.
But then I tried it again, and it ran fine at Ultra Quality for two whole levels.

In an effort to see if it was power related, I upped the voltages to my CPU by 0.025V and to my PCI-E bus by 0.1V, but that was enough to shut my system down completely, and I had to boot back into BIOS and reduce the voltages again. (And I'm scared to do it again for fear of the system not ever booting again...)

Since ATI is dragging their heels in coming up with any kind of response to my ticket with regards to testing the graphics card, I'll ask here in this thread.

Do you think that this could be power related? If so, what would you recommend would be a good ATX2.0 PS for use in this system? I'm just worried that my current PSU is not getting enough juice to my X800XL due to the fact that it has no molex connector on the card, and that I have no 24 pins connector...

Any advice greatly appreciated
Thanks in advance.

Creston

In addition to what Fern suggested (in the other thread), try taking out all but your system's essential components & test again. By running on bare minimum, that could isolate the possibility it's the system's load exceeding your PSUs rated output.

Originally posted by: BeeBoy
I've read the thread and its great i must say. i have asked a couple of people about whether i can use my motherboard with a 20pin connector and 1 guy said no way, another said sometimes, depending on the motherboard and another one said yes, sure.

So the reason i'm writing this is that i just got my computer today and i had a psu already which has a 20 pin connector. the PSU is a Q-Tec 550W.
The system i want to use it in looks like this:

Asus A8N SLI motherboard (has 24 pin connector)
AMD 64 3000+
1GB DDR RAM
XFX Geforce 6600GT Gamer Edition
200 GB Maxtor hdd
Pioneer DVD writer
Thermltake Xaser III ATX tower with 7 built in fans

Now, on the motherboard there is somethign called the EZ plug which is supposed to be an asus invention or something, that ensures stable power flow to the video cards and only requires a 4 pin power connector (i think thats what is called a molex)

So can i use this PSU with this motherboard using only the 20 pin connector or do i need a better PSU, or is it enough if i just buy a 20 to 24 pin converter?

My brother used this very same PSU in his computer (he upgraded the PSU to a vantec and gave me this one, because he bought an XFX Geforce 6800GT)
His setup looked as follows:

AMD Opteron 140
MSI K8T Master FAR2
2GB DDR RAM
Asus Geforce 2 gts
2 * 160 GB HDD
LG Dvd burner
Thermltake Xaser III ATX tower with 7 built in fans (same as the one i have also)

So he says he used this setup with the 20 pin power connector with no problem, but my concerns are about the fact that he didn't have a really good video card then, plus it wasn't a PCIe card either.

So i was wondering if you could help me.

If memory serves, the EZ-plug is used in case the PSU connected to the motherboard is a 20-pin. The EZ-plug is a method of tapping additional power without the need for a 24-pin PSU.

Secondly no need for a 20P -> 24P adapter as that's what the EZ-plug is for & from what's been said around here, the 20P -> 24P adapter could do more harm than good.

 

[Algere]

Flexy, after rereading your original post ("do i need a 24pin PSU" FAQ). Some questions & what not come to mind.

(Q) but what about the extra 4 pins on the PSU plug/motherboard connector ?

These four extra pins on the newer ATX 2.0 PSUs are solely for providing power to the pci-express port . I guess the specs demanded a separation of the power-rails for CPU/motherboard and high-end graphics.
Therefore they put the additional rails on the plug/motherboard which provides +12V, +5V, +3.3 and GND to the pci-express slot.

According to PCI-SIG's PCIe specs (pg. 6), the +5V line isn't used by the PCIe slots.

(Q) So..but i got/plan to get a pci-express card !

pci-express cards will MOSTLY have an external power-connector (6 pin pci-express). You can connect two unused molex connectors from your PSU to this connector on the graphic card via an adapter. If you dont have this adapter - newegg has one
pci-express power adapter

*(!) a single connector/wire on a PSU/connector is usually rated at a max. power draw of 6A. Wattage = VOLTS*A.
The maximum wattage for ONE 12V connector is therefore 72A. The two molex connectors are combined since a high-emd graphic card usually uses MUCH MORE than 72W..therefore it uses two molex which should be ok for up to 144 Watts.

THATS why the pci-ex graphics card SHOULD be able to run fine even WITHOUT the 24pin motherboard connector and WITHOUT a newer PSU with 24pin plug. The card gets enough power already and does not REALLY need the power from the PSU plug.

Thats why the newer boards are USUALLY comaptible with either 20pin PSUs or 24pin PSUS.

**[As a sidenote] A pci-express card with NO external power connector which would get the power solely from the pci-port can (therefore) only draw a max. 72W. The current high-end cards all draw much more power. Eg. a Geforce 6800 Ultra is listed as using as much as 110 Watts. There is no way to do this with just the power coming from the 6A/72Watts rated pci-slot

*)I haven't heard of this 72W figure that the PCIe power plug supplies, but I have heard about the 75W figure that the PCIe 16X slot offers. Based on specs (pg. 4) I quote,

"Change table 4-1 to indicate 5.5 A as the maximum supply current on +12V using the x16 connector as noted below".

Is your 72W figure one & the same with the 75W figure?

**) 75W etc. & does the 6800 Ultra's power figure (110W) include the wattage from the +3.3V line as well, or just the wattage from the +12V line alone?

(Q) My older 20 pin PSU has this extra 4pin connector with the two yellow and two black wires ? Can i use this to "fill up" the missing 4 pins on the 24pin connector on the motherboard ? Isn't that what it's for ?

NO NO NO..DONT EVEN THINK ABOUT IT !!!

This is the 12V CPU connector which you use to provide juice to the CPU, there is another 4 pin connector on the motherboard especially for this.
Dont even think about using this (YES, i saw people considering this option!) - except you need a sure way to fry your board !

There is a smaller (?) number of newer 24pins PSUs out there who actually *do* have
detachable 4 extra pins on the main connector - so you can attach it to the 20pin connector and have a 24pin connector.

But even if it might look about the same....do NOT confuse this with the 4pin 12V CPU connector !

I find this FAQ a moot one unless I'm wrong. Can the P4/CPU 12V plug even fit into a motherboard's 24P connector in conjunction with a PSU's 20P plug?

 

[labonn]

**) 75W etc. & does the 6800 Ultra's power figure (110W) include the wattage from the +3.3V line as well, or just the wattage from the +12V line alone?

I'd sure like for some one to clarify this issue also. How can you pull >100W off a slot only designed for 75W? BFG says my PCIE 6600GTOC needs 105W, but does not provide an extra power connector on the card. I'm getting "Insufficient power" warnings from the card at Bootup. BFG doesn't think it's the lack of an extra power source, but won't explain to me where the extra 30W is supposed to come from. My PSU has dual rails-15&18A. I don't know which rail supplies the GPU...
Thanks for any replies...

 

[Algere]

Is it confirmed BFG said 105W for a 6600 GT OC? Possible they might've misread the info you gave them? e.g. you said 6600 GT & some BFG rep saw 6800 GT. Does sound likely as the 6800 Ultra is said to consume up to 110W & a 6800 GT OC (near 6800 Ultra frequencies) is right below it when it comes to power.

Secondly, from my guess (based on limited info) the 18A rail supplies power to the video card.

 

[jonnyGURU]

Originally posted by: Algere
I find this FAQ a moot one unless I'm wrong. Can the P4/CPU 12V plug even fit into a motherboard's 24P connector in conjunction with a PSU's 20P plug?

Whoa! Put the screwdriver down and step away from the PC!

Am I hearing you right? The 12V 2x2 instead of the extra 4-pins?

This HAS been stated in this thread, but I'll touch on it again since you missed it: The extra four pins on the 24-pin connector is (one each) 12V (yellow,) 5V (red,) 3.3V (orange,) and ground (black.) The 2x2 12V connector is just two 12V's and two grounds.

I wouldn't say this thread is "moot." It is full of a lot of mis-information so you have to be careful and read the whole thing. If anything, this thread needs a good "filter" edit.

 

[jonnyGURU]

Originally posted by: Algere
Secondly, from my guess (based on limited info) the 18A rail supplies power to the video card.

Here's the way the dual rails go:

12V1 supplies power through the 20 or 24-pin ATX connector and any PCI-e connectors (if applicable! Obviously, if you're using an adapter to adapt a regular drive molex, you're not using 12V1.)

12V2 supplies power to the drive Molexes and, ironically enough, the 12V 2x2 connector.

 

[labonn]

oops, wrong button...

 

[labonn]

Originally posted by: labonn

Originally posted by: jonnyGURU

Originally posted by:
Secondly, from my guess (based on limited info) the 18A rail supplies power to the video card.

Here's the way the dual rails go:

12V1 supplies power through the 20 or 24-pin ATX connector and any PCI-e connectors (if applicable! Obviously, if you're using an adapter to adapt a regular drive molex, you're not using 12V1.)

12V2 supplies power to the drive Molexes and, ironically enough, the 12V 2x2 connector.

Per my Antec NeoPower Manual:

12V1 Rail- Supplies the 24-pin ATX connector; 4-pin Molexes to "...drives and other periperals"(inc. floppy); SATA connectors; and the 6-pin PCI Express connector.

12V2 Rail- Supplies the 4-pin Motherboard connector.

They must assume I know which rail supplies the MB's PCI & PCI-E slots, but I don't.
If all slots receive power from 12V1 (216W), and the 6600GT needs up to 105W,
(note to Algere: Yes, BFG knows it's the 6600), then that doesn't leave a lot for 6 HDD, 2 DVDCD/RW, floppy, SATA Controller card, and Wireless Network card, does it? 480W total available, and I don't seem to be able to access all of it.

More comments would be well received...Thanks!

System: PSU-Antec Neo 480; OS-XP MCE05; MB-Abit AN8 Fatal1ty; CPU-AMD FX55; GPU-BFG6600GTOC; HDD-5 Samsung 120GB, (RAID 0+1, w/Hot Spare); RMV'able HDD-Raptor 70GB; Floppy; Promise Tech. SATA Controller TX4; Belkin Wireless Card.
Wanna add VIVO card of some sort and a real soundcard.

 

[jonnyGURU]

Hmm.. Drives on the same rail as the ATX connector? Let me confirm that.....

 

[jonnyGURU]

Ok. You're right. The drive molexes are on the 12V1 with the 20-pin ATX and the PCI-e. So the juice going to the video card ISN'T as clean as that being regulated for the CPU. Bummer.

Guess that's why we need 3-12V-rail or 4-12V-rail power supplies!!

 

[labonn]

Originally posted by: jonnyGURU
Ok. You're right. The drive molexes are on the 12V1 with the 20-pin ATX and the PCI-e. So the juice going to the video card ISN'T as clean as that being regulated for the CPU. Bummer.

Guess that's why we need 3-12V-rail or 4-12V-rail power supplies!!

We're getting there..., but I still don't understand which rail supplies the PCIE Slot with power. (Remember, my 6600 card does not have an extra power connector)

Actually, it's a 24-pin ATX...

 

[jonnyGURU]

It gets its power from the power provided by the ATX connector if there's no power provided by a PCI-e connector.

So you're getting your power from 12V1.

The 12V2 is ony for CPU power.

 

[Algere]

Originally posted by: jonnyGURU

Originally posted by: Algere
I find this FAQ a moot one unless I'm wrong. Can the P4/CPU 12V plug even fit into a motherboard's 24P connector in conjunction with a PSU's 20P plug?

Whoa! Put the screwdriver down and step away from the PC!

Am I hearing you right? The 12V 2x2 instead of the extra 4-pins?

This HAS been stated in this thread, but I'll touch on it again since you missed it: The extra four pins on the 24-pin connector is (one each) 12V (yellow,) 5V (red,) 3.3V (orange,) and ground (black.) The 2x2 12V connector is just two 12V's and two grounds.

I wouldn't say this thread is "moot." It is full of a lot of mis-information so you have to be careful and read the whole thing. If anything, this thread needs a good "filter" edit.

Perhaps you should read again why I said it. It was a response to a quote (rhetorical question ). AFAIK you can't use the P4/CPU12V plug in conjunction with the 20P plug since it wouldn't fit, hence the "unless I'm wrong" & being just that, why would you need a FAQ that says not to connect the P4/CPU12V plug into 4 of the 24-pins of a motherboard's power connector if you can't do it anyways - due to fitting.

I also didn't say this thread was moot, I said the FAQ (the one I quoted) was moot.

Originally posted by: jonnyGURU

Originally posted by: Algere
Secondly, from my guess (based on limited info) the 18A rail supplies power to the video card.

Here's the way the dual rails go:

12V1 supplies power through the 20 or 24-pin ATX connector and any PCI-e connectors (if applicable! Obviously, if you're using an adapter to adapt a regular drive molex, you're not using 12V1.)

12V2 supplies power to the drive Molexes and, ironically enough, the 12V 2x2 connector.

AFAIK that's not how it goes.

The two methods that I know of for power distribution on dual rails are:

Method 1
RAIL 1: P4/CPU 12V (2x2 configuration) plug only
RAIL 2: Everything else that utilizes +12V

Method 2
RAIL 1: P4/CPU 12V (2x2 configuration) & main 20/24P plug
RAIL 2: Everything else that utilizes +12V

 

[jonnyGURU]

Originally posted by: Algere

Perhaps you should read again why I said it. It was a response to a quote (rhetorical question ). AFAIK you can't use the P4/CPU12V plug in conjunction with the 20P plug since it wouldn't fit, hence the "unless I'm wrong" & being just that, why would you need a FAQ that says not to connect the P4/CPU12V plug into 4 of the 24-pins of a motherboard's power connector if you can't do it anyways - due to fitting.

I also didn't say this thread was moot, I said the FAQ (the one I quoted) was moot.

Ah! An FAQ. I thought you were talking about this thread.

So it's agreed. It WOULDN'T make sense to NOT use the 2x2 connector REGARDLESS of whether or not you were using a 20 or 24 pin connector and you WOULD NOT use the 2x2 connector in conjunction with a 20-pin ATX connector in a 24-pin motherboard interface.

I swear to god I read it three times and it sounded as if you wanted to plug a 20-pin and a 2x2 into a motherboard's 24-pin connector!

I really do think this thread is full of "traps." Right off the bat with the first post it's said that the extra 4-pins is specifically for PCI Express.

As for your observation of the two 12V rails; I'd like to see where you got your information from. Seriously. I got mine from my PSU tester (after labonn corrected me from what he found in his Antec manual.) Method 1 seems to correspond with what I've witnessed, but I've yet to see a configuration that uses Method 2. And if there was a configuration that used Method 2 than my power supply tester would not be able to test it since 12V2 is tested by plugging in the 2x2 connector.

I wish Method 2 was the only means. It makes more sense to me to feed power seperate from the drive, fans, lights, etc. to the motherboard via the ATX connector AND the 2x2. I've just yet to see it performed in practice. If there's a specific power supply that you know of that splits the rails as per "Method 2," tell me what it is so I can buy one and plug it into my tester to see what the results are.

 

[Algere]

Method 2 (excuse the crooked scanning job )


P.S. Although the link shows SATA with "+12V 2" which is similar to "+12V2" (CPU + Mobo), I previously contacted Enermax customer/tech support a few weeks back and he said it followed method 2. So it either follows method 2 or...

Method 3
RAIL 1: CPU/P4 (2x2 config.), main 20/24P plugs, & SATA
RAIL 2: Everything else +12V dependant

Now with Method 3. Either I initially in the past read it wrong & IMO Enermax shouldn't have listed the diagram with SATA with "+12V 2" in the manual or Enermax's (Maxpoint) customer/tech support agent gave me the wrong info by saying it followed method 2. However I'm leaning towards it being method 2 since the cables are seperated by 3 nylon sleeves:

Sleeve 1: PCIe 6P & fan monitor cable
Sleeve 2: P4/CPU 4P + main 20/24P
Sleeve 3: Floppy, 4P molex, & SATA

 

[jonnyGURU]

Ah! Yes. Look at that. The ATX connector, the 2x2 and the SATA all use 12V2 power and the drive Molexes uses 12V1.

Well.. That just BASTERIZES everything. Now you're spinning motherboard and CPU fans and any other fans you have plugged into your motherboard off of 12V2, your hard drive motors off of 12V2.. but your supposed to have clean 12V2 for your CPU?

And then you've got other drives, including your floppy, fans, lights, etc. using 12V1.. so you're not getting clean power for your PCI Express video card which also uses 12V1. PLEASE tell me Enermax made a major typo.

 

[Algere]

Edited for hopefully that's the case.