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

[Googer]

Originally posted by: Go Go Gadget
A bit expensive for my tastes at 200+ dollars, but thanks!

I will now go out and get a new power supply.


edit: those special 6pin cables look awesome though.

No one ever said SLI was ever going to be cheap. My advice is get it (the recomended PSU) and don't cut coreners here. You will deeply regret it later.

 

[Go Go Gadget]

I know not to cut corners, and I am not doing SLI, just a single 6800GT. One.

I don't plan on cutting corners but I also dont plan on spending that much. A coolermaster 450 or 480 should do fine I think

 

[jonnyGURU]

Originally posted by: ceefka
There are a few questions remaining:

What's that -5V thingy on various PSU's (usually at 0,5A) ? MSI and Gigabyte say they need that but hardly any ATX 2.0 with 2x 12v supplies that -5v.

I am planning on having a Yesico http://www.yesico.de/products/550atxt.htm FL-550ATX(T) with TMS powering a nF4 Ultra board. MSI says on their nF4 Ultra and up mainboards the 12v ATX needs to be greater than 18A. I can't figure out if they mean the combined A of the two available 12v rails or any of the single rails?

Don't worry about the -5 or -12. They're usually only 0.5A. They're only included to make power supplies backwards compatible with systems with ISA slots or amplified on-board sound or for certain serial devices (not USB, but serial. As in 9-pin.)

I'm sure for 99% of the folks here, we could cut the -5 and -12V leads off their ATX connector and the PC would keep on putting along without issue.

Hmm... /Me contemplates a little test.

 

[FastEddie]

Hey jonnyGURU--that's completely true, with the exception that MSI utilized the -5v pin to enable the onboard 24-bit Creative chip, which made having it very necessary for both the K8N Neo 4 Platinum & K8N Neo 4 Sli (essentially both the same board).

And there are quite a few problems in SLI Land using the dual rail/tri-rail psu's when coupled with dual 6800Ultra's. I've been propounding on the subject for three and a half months, and I get five emails a week about helping "stabalize" Sli boxes using high powered Ultra's a paired with these multi-rail psu's. I just returned one Sli box to the owner that was using a brand new Thermaltake Purepower 680W (with three 12v rails), where the box would just shut down after about three seconds into Doom 3. The box worked great with two 6600GT's, and with one of the 6800 Ultra's, but add the second Ultra and it would just shut off when the game was loading. Swapped in a TruePower 550W EPS+12 or a 500W Athena Power (EPS+12) and everything worked fine. Then sent off an email to Thermaltake asking if anyone there had actually tested the Purepower 680 with 6800Ultra's in Sli.

 

[jonnyGURU]

MSI is STILL using the -5V???

Jeez!!!

I had so many problems with MSI boards with on-board sound and MOST power supplies in the past because PSU manufacturer's don't prioritize stability or cleanliness on the -5V rail. I would end up with people RMA'ing MSI boards that were perfectly fine, but had symptoms like staitc in the sound, no sound, buzzing sounds coming from the speakers....

The worst culprit I found for poor -5V effecting MSI boards: Enlight.

As for the dual rail problem you're talking about: PSU manufacturers are faced with a double edged sword. Intel doesn't want rails spec'd out with 20A or more on each rail or they won't "approve" them. I read that in Intel's specs and turned BEET RED. That's BS! Intel is going to limit how much power I can have on a rail?

 

[jonnyGURU]

Umm... You know what?

An Antec Neo Power won't work with an MSI board.

There's no -5V rail AT ALL!! Take a look at the specs... and then the 24-pin connector. No white wire!!!

 

[FastEddie]

Exactly. There are a few psu's that are mixed in spec, that are 24-pin EPS and still retain that white wire.

 

[jonnyGURU]

I didn't have a chance to go through the whole thread, but has anyone corrected flexy for his statement: "These four extra pins on the newer ATX 2.0 PSUs are solely for providing power to the pci-express port ."

This simply isn't true. Proof in two forms: First being the number of boards that are out there that have 24-pin power connectors that don't even have PCI Express slots. Secondly; one of the four additional pins is 5V. You'll note that a PCI Express slot has 12V and 3.3V, but no 5V. So how could the extra 5V be "soley for providing power to the PCI Express port?"

The extra four wires are merely a means to deliver additional power to many facets of a motherboard. CPU, RAM, AGP and PCI Express. Not "soley" PCI Express.

Sorry if I'm just repeating what someone else has already pointed out. I just noticed seefka's post going unanswered and had to chime in.

 

[jac0b84]

Any suggestions for a power supply to replace my seemingly inept one?

 

[Googer]

JonnyGuru is correct.

 

[jac0b84]

Answered my own question :

http://www.anandtech.com/mb/showdoc.aspx?i=2358&p=20

 

[Romano7]

Guys, hi look how I've made my site www.jesus-flower.com

 

[imported_ceefka]

jonnyGURU and FastEddie, thanx for your wisdom. I was very interested in the nF4 Ultraboards of MSI or Gigabyte but it looked like there was no adequate PSU for them.

Yesterday I ran into this one http://atro.nl/product_info.php?products_id=5243 it's in Dutch, but the numbers will come across, I suppose. There's a short review in English here http://www.pcreview.co.uk/reviews/Miscellaneous/Tagan_TG480-U22/ The dual 12V rails are switchable from 2x 20A to 1x 30A. It's also real quiet, they say, almost too good to be true.

As far as I know, it's a German product which is readily available in The Netherlands. Yeehah!!

Romano7: Good job!

 

[FastEddie]

That Tagan (TG480-U22) is a real decent unit. If I were to design a dual rail psu specifically for Sli, it would be very much like this one. In dual mode, both rails carry 20a, but when combined, they give 30a on a single 12v rail. This sounds like near perfection for Sli.

Can't find a manufacturers link (MaxPoint) though, to see how they are describing the combining of the two rails, but from what I'm able to ascertain, there is a switch that allows for running two seperate 12v rails with 20a available on each,m or switched to single 12v rail, with 30a available. The latter would be perfect for Sli.

Great find ceefka, the Tagan should handle anything you throw at it.

 

[jonnyGURU]

I doubt that Tagan is actually any different than any other dual rail 20A/20A PSU on the market.

I wish they took it apart for that review. I guess I'll just have to find one for sale in the US, buy it, take it apart, blow it up and give you my $.02.

 

[FastEddie]

Originally posted by: jonnyGURU
I doubt that Tagan is actually any different than any other dual rail 20A/20A PSU on the market.

There is a difference. There's an external switch that changes the mode from two 20a 12v rails, to a single 30a 12v rail. All other dual/tri rail psu's lack that ability, and as we already know, have no internal means of combining the multi-rail output in any way shape or form. Tagan is on to something with the 480-U22.

 

[jonnyGURU]

I'm well aware of the switch. That doesn't change my opinion.

Most "dual rail" power supplies will actually let you combine the power of the two rails as it is. Some companies hide this. Others don't (like PCP&C.) I bet all that switch does is bypasses some sort of filter. Perhaps a capacitor. I need to see the inside of one. But I don't think there's anything "ground breaking" with that switch.

Anyone know where I can buy one in the states?

 

[imported_ceefka]

I have not seen many other dual rails with figures like 20/20. I've seen 18/16 like the Antec Phantom or the Yesico 550 and those with 15/16 which I do not dare to use etc.

BTW: I realized that the MSI Neo4 Platinum does not depend on a -5v. the Diamond does.

I asked MSI recently if the Yesico 550 will be OK with the Neo4 Platinum. They said "This PSU should work." which is not a very decisive answer
The Yesico is a 24pin (combi-plug) has 12v1 @ 18A and 12v2 @ 16A, no mentioning of combining these two.

 

[jonnyGURU]

ceefka: No doubt 20A/20A or even 30A on a single rail is a great spec. All I'm saying is that I think the switch on the back is a gimmick.

As for MSI: You'll get that type of answer from them with any question like that. Will this PSU work? Will this RAM work? They don't make power supplies and RAM. If they gave you a difinitive answer, there'd be a degree of liability if they turned out to be wrong, even if every person at MSI has the exact same PSU or RAM as you.

I try to point people to the PSU calculator at http://takaman.jp/D/?english to help figure out what power supply is best for them and then, instead of looking at the total wattage, look at the break down of rails and match those specs up as best as possible.

 

[imported_ceefka]

jonnyGURU. that is a helpful link.

I do not have much experience with asking manufacturers, but you're probably right because I got a similar answer from Gigabyte. Now that I actually have only 2 choices left I will be going over to some DAW forum to discuss noise. Funny thing is:

Yesico 550 is fanless (0dB noise) price ? 219,00 (!!)
Tagan TG480 U22 (21 - 22 dBA @60% load, max. 28 dBa full load, not bad at all) price ? 98,00 (less than half of the Yesico)
The silenced 4HE 19" case has 1x120mm and 2x80mm controlled fans all rated @ 9-12dBA.
The CPU cooler will be Zalman 7700 CpAu or Thermaltake 103 Fanless (probably either the PSU or the CPU-heatsink will be fanless, did you know that people cool Prescotts with the TT 103?)
Balancing every ?, dBs and ºCs

I thank all of you for input to my questions. If all goes well I expect to build my rig in april 2005. I'll let you know.

 

[madmickey]

test

 

[POSTILL]

I've got plans for an Abit AN8 (Pci-e) motherboard to go with my AMD 3500+.

Having problems deciding on a power supply. Was sold on the Enermax 420W

Noisetaker until I heard the cabling was impossibly stiff. Now considering the

OCZ powerstream 420W. Is the OCZ a better choice?

 

[jonnyGURU]

I don't know how Enermax's cables could be "impossible."

Most of the cables are identical between the OCZ and Enermax. Typical Red, Black, Black, Yellow.

The OCZ has some rubberized cables that are rather stiff, so if anyone's cables are "impossible" it would be theirs.

The Enermax ATX cable has a nylon sheath on it, but it doesn't make the cable any stiffer than if it didn't have one.

 

[jim1976]

Very nice thread. Glad to see it sticky.

A have a question

I had a TT480W which recently died on me and now looking for a good one. Which one do you ppl speculate that would be more futureproof for dual cpus and next gen gpus?
Will an EPS12V be really necessary? I was thinking of something like the Enermax 600W, would that be sufficient ?(not EPS12V)

 

[Notsohappyharry]

Thanks to all for the wealth of info on the 24 pin vs the 20 pin connector. I am building my newest computer for the first time and the 20 pin connector had me frustrated.

I would also like to add if anyone building a new system is considering not adding a floppy drive, change your mind! I have a Western Digital Raptor 74GB Serial ATA drive I am trying to get Windows to regonize so I can format it. It seems the drivers are not part of Windows XP Pro. The setup will not regonize the drive without the drivers and the only way to add the drivers during installation is by floppy drive! I have the bios set to boot to CD but the installation still wants access to the floppy drive for the missing drivers.

Thanks again for a great forum!