9800GTX + ACE 500W power supply - no bootup!

[amund_nor]

I am making a free build for a friend with some old components of his and of mine. I had a XFX 9800 GTX laying around and wanted to give it to him. I found that the power supply from my friend's old PC didn't have the two required 6-pin cables, so I bought a couple. The ones I could find were 8-pins, but i just split off two of them (with knife, though...) so it would fit. Now the problem is... I can boot up the computer with the 9800GTX plugged in the PCIe, but as soon as I try to boot up WITH the two 6-pins connected to the GPU, _NOTHING_ happens when i press the power button. Then I unplug the two 6-pins from the GPU, it boots up agian.

Now... What is causing this? Is it just the 500w PSU that can't handle it?
The PSU has a 12V1 15A and a 12V2 16A. I've found that the 9800GTX needs at least 26A on the 12V rails. But I know little about _this_ stuff, so I'm kinda lost; am I supposed to add up 15+16A, which leads to 31A? Or is that wrong...?
WHY DOESN'T IT BOOT?

TLDR; can ACE 500W power supply (12V1 15A, 12V2 16A) supply an XFX 9800 GTX card?

Edit: Forgot to add rest of specs...
-Core 2 Duo E8500
-4Gb Corsair 800Mhz DDR2
-MSI G41M4 Mobo
-2 HDDs
-1 DVD RW
-And the almighty XFX Geforce 9800 GTX

 

[clutchc]

First, I have no idea what you are actually using for your 6 pin aux cables to the gfx card. Molex to PCIe adapters? Something your haywaired into the PSU?

But assuming the PCIe cables are satisfactory, it would appear the cheap "500W" PSU can't handle the startup load the card demands. The total 31A (??*) capacity of that PSU's +12V rail is also shared by the processor, drives, fans, MB, etc. When the power to the 6 pin ports on the card is removed, the card is essentially turned off. Therefore the load on the +12V rail is lessened. And you get the PC to boot... w/o a display.
My advice; get a better PSU or a less demanding card.

Btw, the amp capacity of the +12V rail isn't the only thing to be aware of. Look for the total wattage the rail(s) can handle. It may share that capacity with another voltage rail.
That "500W" PSU is far from a real 500W PSU. Highly over-rated with those small +12V rails.

* According to Nvidia, the 9800GTX is a 140W card maxed out: http://www.geforce.com/hardware/desktop-gpus/geforce-9800-gtx/specifications
Using Ohm's Law, that would require 11.7 amps from the +12V rail, not 31A.

 

[amund_nor]

Alright, thank you! 😉
Yeah, those are molex to 6-pin. I'll tell him to buy a new PSU then. I'd figure the Corsair CX 500W should do the trick. (Really, no high budget here..)

But, though... Are you _sure_ that's the problem? That the solution is that the cheap Ace 500w can't handle the _STARTUP_load?

Anyways, thank you very much for the answer.

 

[jb6684]

ClutchC is right, your current power supply can't supply enough current. NO, you can Not "add the two rails together." Get something like the Corsair CX600, it's only a few dollars more than the CX500 and it removes all doubt that you have enough power....

While they rate the average power a GPU draws, they rarely rate the Peak Power, which you must have to support the start-up/in-rush current. Here's a Great article showing that, and, it's about DOUBLE the rated or power for the card... (so, about 24--25amps in the case of the 9800)

http://www.tomshardware.com/reviews/radeon-r9-290-and-290x,3728-4.html

 

[clutchc]

Alright, thank you! 😉
Yeah, those are molex to 6-pin. I'll tell him to buy a new PSU then. I'd figure the Corsair CX 500W should do the trick. (Really, no high budget here..)

But, though... Are you _sure_ that's the problem? That the solution is that the cheap Ace 500w can't handle the _STARTUP_load?

Anyways, thank you very much for the answer.

Well... I'm as sure as I an be not being there to test it myself. There's no way anyone can be 100% sure just from someone's description. It is just my opinion. Do you have a different PSU you can test with? Or a less power-hungry card you can test with? Do you know the card is OK?

 

[amund_nor]

Btw, which would you rather recommend?
A Corsair CX 600W M or a OCZ ModXstream Pro 500W ?
I'd easily go for the Corsair, especially since the price is only 40NOK more (6.5 USD) than the OCZ.
- And the Corsair CX 600W M is only 20NOK (3.25 USD) more than the CX 500W M.

....Or.... I think we're ending up here with getting a HD 5770 from another friend, which is a little less power consuming and more powerful. I hope it'll work!

 

[amund_nor]

Ah, two more replies, thank you so much!

Good article, jb6684, thanx! And yeah, I'd think about the CX 600. But the CX 500 was actually 22% off atm! 😛
Though, as said, I think we're going with a HD 5770 instead, which is a bit less power hungry.

Clutchc, haha yeah I understand. It's never an easy task to help someone online, not really _being_ there makes a LOT of difference.
I don't have another PSU hanging around, nor do I really know if the card is in good state, haha!

All in all, thank you so much for your help! I'll bump this later to tell if the HD 5770 worked well.

 

[clutchc]

Btw, which would you rather recommend?
A Corsair CX 600W M or a OCZ ModXstream Pro 500W ?
I'd easily go for the Corsair, especially since the price is only 40NOK more (6.5 USD) than the OCZ.
- And the Corsair CX 600W M is only 20NOK (3.25 USD) more than the CX 500W M.

....Or.... I think we're ending up here with getting a HD 5770 from another friend, which is a little less power consuming and more powerful. I hope it'll work!

The Corsair has better specs. But try the HD 5770 to be sure the problem isn't a bad 9800GTX. The HD 5770 is a 108W card. It might still be too much for the cheap PSU.

 

[amund_nor]

Ahh damn it. The HD 5770 still requires too much power for the 500w PSU. I have friend with an HD 5750, though.... I thibk I'll try that. If THAT doesn't cut it, then i have 9500GT.
Uuuughhhh......

 

[erikwal]

Immediately get rid of that Ace 500 W PSU!!
I would like to call them downright dangerous. Two big transistors in my brother's PSU basically blew up this weekend while doing a simple stability test. A slightly overclocked Core 2 Duo E8500, only one hard drive and a GeForce 9800GTX

After a few minutes with Furmark, his wife came and said that the computer smelled burnt. A few seconds after that, before I could turn it off there was almost like a bang and a big white/green flash from the combustion of copper in air.

When this happened the power consumption meassured at the wallsocket was only 380 watts.

In other words: They don´t seem to have the simplest overload or over heat protection, AND the specifications are false.

I assume you have the same model because the specifications of the two 12 V rails are exactly the same.

A comparison:
============
With exactly same load scenario but using a "Cooler Master B600 ver. 2" PSU instead, the power consumption is 55-60 watts lower than with the Ace PSU and the PSU casing is barely lukewarm.

GET RID OF THE ACE before something catches fire!

/ Erik

Edit: No, the fuse was NOT still whole like I said first.

 

[amund_nor]

Oh, sh*t sounds dangerous! I was building this thing for my friend. I think the end of the story was that I bought a cheap 550w Corsair TX supply for him 😉 So the ACE model is not in use anymore