HD 2900XT 8 pin connection issue

[Dima]

Hi,

I just got a new Thermaltake Toughpower 750W power supply.
When I have 8pin + 6pin power connection, system reboots unexpectedly after
playing for about 30 min.
If I have 6+6pin power connection, the games run fine.
I didn't overclock the card.

System specs:
Asus P5K Deluxe
Intel E6600 Core2 Duo
HIS HD 2900XT 512MB
SB X-Fi
Seagate ES 750GB HD
Asus DVD burner

Here's the answer I got from Thermaltake
"It can be the video card's power distribute problem. You have enough power
for your system. Easy way is just stay with 6+6pin."

Any ideas what could be the real issue?

Thanks.

 

[nonya a. nonymous]

i haven't heard of a "power distribute problem" on the 2900xt.
i've got a 2900xt 1gb and run it fine with a 700watt fps and
use a 6-pin and a 6-pin to 8-pin adapter.
do you use the 8-pin alone or with the 6-pin?

gigbyte n650
e6600
diamond hd2900xt 1gb

 

[First of One]

Are you using the 8-pin connector directly from the PSU, or through a
6-to-8-pin adapter? According to Thermaltake's web site
(http://www.thermaltake.com/product/Power/ToughPower/W0116/w0116.asp), both
methods are possible, so try the other method.

 

[Dima]

It's 8 to 6 pin adapter, not the other way.
I have it.
I'll wait for an answer from HIS and maybe try maybe replacing the PSU.

 

[First of One]

The Thermaltake page says the PSU also has a dedicated, non-modular 8-pin
PCIe connector.

Of course, all this is only relevant if you intend to overclock.
Overclocking is not recommended with the stock cooler, because the fan is
loud when spun up to 100% duty cycle.

 

[Dima]

Yes,
That's what I was using. Dedicated 8-pin PCI express connection.
There's an adapter that converts 8pin to 6pin.

When I was using 8 pin connection, I wasn't overclocking.
But still I got to find what's causing the unstability.

 

[First of One]

The dedicated 8-pin line is on the same 12V rail as the main 24-pin ATX
connector that powers the mobo and CPU. Excessive current draw on that rail
may be the cause of instability. Hell, it could even be the PSU's
overcurrent protection kicking in, causing the reboot.

So have you tried using the 8-to-6-pin adapter instead of the dedicated
8-pin line? To the PSU, this is same as using the 6+6 pin connection. The
6-pin PCIe connectors are on a different 12V rail.

And just so there are no misunderstandings, the 6+6 pin connection is
perfectly acceptable if you don't intend to overclock. 8+6 pin isn't any
"better".

 

[Dima]

well, I was going to do some overclocking of RAM, as my card has 1ns chips.
I'll try your idea. Thanks.

 

[Dima]

Got the 8pin to 6 pin adapter and it works great on that wire.
So it must be the video card?

 

[First of One]

Nope. The video card is fine. The PSU is fine. The cause of the instability
is you overloading the first 12V rail on the PSU by using the dedicated
8-pin line.

The PSU gave too many choices on ways to hook up components. Some of these
choices weren't well thought-out.