Installing XFX 4870 - power cables

I'm trying to install a new graphics card to my PC that's a XFX HD 4870 & I'm having a few probs as I know little about hardware. Anyway, the problem is the card has 2 power sockets on it & the guide is expecting this to be connected via 2 PCI express power cables directly from the power supply. After having a little look around the bowels of my PC there appear to be none. The card does come with 2 seperate cables that plug into these two 6 pin sockets on the card, they then split into 2 what look like standard power cables( white connectors with 3 prongs, 1 prong is missing on all of them). I could use these cables provided instead but as they split into 2 & there's 2 cables, I would need (I assume) 4 spare power sockets to plug them into & I only appear to have two. Would this card work properly if I use these cables provided and only plug in one of the sockets from each cable into my two spare power connectors? I was aware that I needed a reasonably powerful power supply for one of these cards (I have a 550W supply that I thought would be just about adequate) but wasn't aware that I might have a problem with the power cables. Anyway, is there anyway to get this working with my existing setup or do i need a new power supply? Thanks for any advice.
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  1. It sounds like the connector you're talking about is like this:

    If that's the case, I think you should be able to use it if you have all four of the molex (white four-pronged) connectors plugged in.

    What's going on is that a four-pin molex connection can't handle as much electrical current as a six-pin PCIe connection, but two molex connections combined can. Basically, in your situation, two molex connections = one PCIe six-pin connection. It's not the ideal way to do it, but a lot of card manufacturers will include the adapters for people in just such a case as yours.

    Now, since you only have two free molex connectors, that could be a problem. Do you have any free SATA power connections? They do make SATA-to-molex adapters (picture in this link), so if you have two free SATA connections, you may be able to jury-rig them into two additional molex connections, which you can then jury-rig into your second six-pin PCIe connection.

    So it looks doable in theory, but that's also making so many conversions that I'm not going to make any guarantees that the whole thing won't just catch on fire.
  2. Thanks for the info, looks like I'm gonna need a new power supply then :( Any recommendations on power supplies that'll have two of these PCI express cables & enough power for one of these 4870 cards all at a reasonable price?
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