4870 pci-e power supply adapter questions

[pschweig]

Hi

I posted this over in the video card forum before someone pointed me towards this forum.

I am considering buying an ATI 4870. I currently have an X1950XTX which uses 1 6-pin pci-e power connector. I have an Antec SP 500 PSU which was supplied with only one 6-pin pci-e cable. I believe that the 4870 requires 2 6-pin connectors.

I have found this adapter which takes 2 molex power connectors and adapts them to a 6-pin pci-e connector

PCI-E adapter on ebay

Has anybody used this kind of adapter to run a gfx card? Are they reliable or is it not recommended to use this kind of product?

I read that my PSU has 2 12v rails. Does the power for the gfx card have to come from a particular rail on the PSU? If so, how can I tell which cable is linked to which rail?

If I do use the adapter should I use 2 molex connectors that are on the same cable from the psu? Or does it not matter?

Will it matter if other molex connectors on the same cable are powering HDDs or DVD drives? Should I seek to use 2 molex connectors on a cable that is not powering any other devices? From reading the 12v rail sticky on this forum it seems that it would be preferable to use a cable that isn't being used for anything else. I have a cable that is only powering a couple of case fans (using pass through connectors). Would that cable be suitable to adapt to the PCI-e connector?


Phew - what a lot of questions
any help is much appreciated

thanks
paul

 

[mpilchfamily]

The adapter would be fine if the PSU was actaully good enough to support your system with that card. Fact is it isn't, and the Antec SP line is not a very good line of PSUs to start with. If you want to move up to the 4870 then you better get a new PSU as well.


The Sp 500 only offers about 24A to the combined 12V rails. Upgrading to the 4870 puts your system's 12V power needs closer to 28A or more. So you'll need a new and better quality 500W PSU. That older model just doesn't offer the amount of power to the 12V rails that newer models of the same size do today.

 

[pschweig]

ok thanks for the advice.

Would my current PSU be capable of powering the 4850?

thanks

 

[Jessica69]

The link below is to ATi's list of certified power supplies for single 4800 series graphics cards.......browse to your heart's content.

http://ati.amd.com/products/ce...wersupplies.html#pstop


The list is broken down by manufacturer and cert'd power supplies for that manufacturer shows what cards it can power....some cannot do a 4870/4850, some can.

I'd also pay attention to what wattage different manufacturers have cert'd for the 4800 series of cards.....some manufacturers/rebadgers have power supplies as low as 425W-500W cert'd for the 4850/4870, while some have nothing below like 700W.

(I think this directly equates to the quality of the different manufacturers out there......for instance, Topower has nothing certified for the 4800 series of cards below 850W while Corsair has the HX520 certified for both 4800 cards....something to think about.)

 

[mpilchfamily]

Originally posted by: pschweig
ok thanks for the advice.

Would my current PSU be capable of powering the 4850?

thanks

Re-read my post.

Originally posted by: mpilchfamily
The adapter would be fine if the PSU was actaully good enough to support your system with that card. Fact is it isn't, and the Antec SP line is not a very good line of PSUs to start with. If you want to move up to the 4870 then you better get a new PSU as well.


The Sp 500 only offers about 24A to the combined 12V rails. Upgrading to the 4870 puts your system's 12V power needs closer to 28A or more. So you'll need a new and better quality 500W PSU. That older model just doesn't offer the amount of power to the 12V rails that newer models of the same size do today.

 

[pschweig]

Originally posted by: Jessica69
The link below is to ATi's list of certified power supplies for single 4800 series graphics cards.......browse to your heart's content.

thanks that's useful information. Looks like I'm out of luck. Bit annoyed because I thought a 500W PSU would keep up with single card gaming for a few years. :frown: Seems that there's more to choosing a PSU than just the watt rating.

Originally posted by: mpilchfamily
Re-read my post.

Originally posted by: pschweig
I am considering buying an ATI 4870.

Originally posted by: pschweig
Would my current PSU be capable of powering the 4850? .

 

[mpilchfamily]

Yes there is allot more to sellecting a PSU then just the total wattage. You have to know how many amps are supplied to the combined 12V rails. You also need to know if its a good quality PSU. You can have 2 PSU with very similar stats as far as wattage and amperge go. But if one uses very cheap parts, thus costing less, then it may not be able to live up to its specs. It could also supply "noisy" power. Meaning the voltage is a bit unstable which will affect the perfromance of your system and could damage parts over time.

In the case of your old Antec SP 500 there where allot of issue with early batches of those PSU having bad caps causing the PSUs to fail within 18 months. This was latter fixed but the design of the PSu still doesn't offer enough power to the 12V rails to support the upgrade your looking to make. Case in point is my old Hyper Type-R 580W PSU. While it is SLI complient and is rated to support a pair of 7900GSs it would not run my system with my 7900GS and a 7300GT running. There where constant power issues. The system would turn on but there where problems. So i hade to take out the 7300GT, which BTW doesn't require aditional power input from the PSU. Then i tried to OC the system. Hit a wall at about 2.6GHz on my Opti 165 (1.8GHz stock). After i got a Corsair VX550 i was able to OC the system to 2.9Ghz. The problem was the amount of Ripple (noise) on the 12V rail causing unclean power. 580W should have been more then enough for the system but it was a cheap crappy PSU that couldn't sustain the power it claimed to have. The Unit is rated to offer 30A max on the 12V rails. Yet it couldn't supply more then 26A and even then it couldn't hold that for very long.