8-pin pcie, adapter?

[Nathelion]

This is not an immediate concern for me as I'm not planning on purchasing the HD2900XT any time in the near future (or ever, actually), but I'm curious since I have a older PSU (Silverstone Zeus 750W) that doesn't have one of the new 8-pin pcie power connectors: Is there such a thing as an adapter from x number of molexes/pcie 6-pin connectors to pcie 8-pin that can acually handle the full 225W? I have been looking around on some sites, and the only adapter I found was from a single 6-pin, which would only give 75W. I figure you'd need no less than a 3-to-1 6-to-8 pin pcie connector adapter to actually make the full power quota?

On a related note, what is the maximum power draw through a 4.pin molex connector? I'm mostly just curious.

 

[HardWarrior]

If there aren't converters now, somewhere, I expect they're just around the corner, unless there's some electrical reason that it would work. Do 2900's pull more than 3x75watts@12amps?

 

[Zepper]

A 6-pin will probably work OK. What is the actual current draw that connector has to support?

.bh.

 

[HardWarrior]

The manual for my RS-850 says that pins 1-3 are +12v and 4-8 are COMs, whatever those are. I'd find out for sure before I slapped converters on, though.

 

[Nathelion]

Originally posted by: Zepper
A 6-pin will probably work OK. What is the actual current draw that connector has to support?

.bh.

Well technically you're supposed to be able to draw 225W through the 8-pin, that'd make ~19A at 12V.
The PCIe slot also provides 75W, and so does the 6-pin PCIe connector. I figure the maximum power draw of an HD2900XT over one 8 pin, one 6 pin, and the mobo would be 375W theoretically. More juice than your regular complete system, in other words.

 

[Zepper]

Real Molex Mini-fit contacts are supposed to be able to handle 9 Amps each, so 3 pairs should offer 27A total. Thus even if they are using cheap Chinese contacts, the 6-pin PC-X connector should still cover it. An an adapter won't change anything as the total current is still carried by 3-pairs only at some point. You could treat your contacts to some Caig Labs Deoxit Gold (formerly called Pro Gold) just to be sure.

Besides, that connector is the same as the EPS12V (dual CPU 8-pin) which you do have). You have more than enough connectors with that PSU including the adapters that came with it to rig up almost anything that might come along.

.bh.

 

[Nathelion]

Cool stuff. Thanks for the info. I just realized there's a ton I don't know about power supplies

 

[AdmiralJamrep]

http://ati.amd.com/products/Ra...2900/requirements.html

As you can see there, the 8 pin isn't a flat out requirement. However, you'll be unable to use the overdrive overclocking feature in catylist control panel. I'm actually in the same quandry you're in, since my brand new Antec truepower trio 650 doesn't have an 8 pin PCI-E connector, which is an annoyance because I'm on vista and so overdrive would be (AFAIK) the only way I could OC it at present. Anyone have any recommendations?

 

[Matt2]

Originally posted by: AdmiralJamrep
http://ati.amd.com/products/Ra...2900/requirements.html

As you can see there, the 8 pin isn't a flat out requirement. However, you'll be unable to use the overdrive overclocking feature in catylist control panel. I'm actually in the same quandry you're in, since my brand new Antec truepower trio 650 doesn't have an 8 pin PCI-E connector, which is an annoyance because I'm on vista and so overdrive would be (AFAIK) the only way I could OC it at present. Anyone have any recommendations?

Use RivaTuner v2.02. I am using a 2900XT on a Silverstone Strider 560w PSU with only 2x6-pin connected and I am happily overclocked to 825/910

 

[SparkyJJO]

The extra 2 pins are only grounds (that is what COM is), I don't see how they can provide any more power really

To enable overdrive in the CCC all you need to do is connect those two pins together with some wire or something. Someone over at XS did that and it enabled him to use CCC to overclock.