I have a question concerning my connection of a X1900XTX to a 480W Silent Tagan power supply (model is about 2 years old). I am using a 6 pin to 4 pin(x2) adapter. Should I be connecting 2 power cables on separate rails to the card via the adapter? At the moment I am only using one connection/rail and I have read that I should be using two when connected to an older type power supply.

Ideally they tell you that same as for 2molex 6800U agp's but its not always possible and likes of a good Antec TP550 can handle it and Antec have stated this, I aint using ATI cards but in mines I ger onscreen warnings if powers low and cards declocks till problem is fixed, and if no power to fan I get siren (buzzer on card) going off.

I have not had any warnings or issues so far (only been a week). Is there any way the performance of the card could be degraded without any warning signs - am I losing performance without my knowing.

Ideally you should have the GFX card one on 12v rail and anything else on the other 12v rail (if you have a dual rail psu).

As long as the +12v rail is stron (meausured in Amps) then you should be fine.

If you had power issues you would have known by now.

oweneades said:

Ideally you should have the GFX card one on 12v rail and anything else on the other 12v rail (if you have a dual rail psu).

As long as the +12v rail is stron (meausured in Amps) then you should be fine.

If you had power issues you would have known by now.

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That is of course very difficult with a dual rail PSU. ATX 2.** on, wanted 12v2 for the cpu alone. That loads everyting else on 12v1. In reality some manufacturers don't take much notice of the ATX spec and spread the loads on different rails. The thing to note is that the 12v rails in most cases comes from the same source. The "rail" is only a 20A/240VA current limiter with maybe a zener diode to clip over 12v. The thing to look for is the combined 12v wattage, don't just add the rail currents together.

For a card like the XTX, for a PSU without a 6 wire PCI-E feed. You should connect to two different molex feeds. Not because it's connecting to different rails, it's not, you would have to tap in to the motherboard connectors for that, besides some of the current comes from the PCI-E slot. But because one 4 wire molex only has one +12v conductor and depending on the wire gauge may start to get a bit warm pulling a lot of current though it. And the longer/thinner the wire and more bundled, the more it derates and the greater the voltage drop, = low 12v. One XTX per molex feed maybe alright, but don't put anything else on the same feed. IIRC 20AWG is about 11A (LVDC) chassis regs, but don't quote be on that.