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So I have an old Dell from 2007. I need my graphics card (NVIDIA 9800GT) updated to something like this.

I currently have 1 PCI Express 2.0 (75W) slot, but I've heard that newer motherboards have PCI Express 2 with 150W, so my question is:

  1. Will that graphics card work? (Not sure what the PCI power requirement is)
  2. Assuming that that the graphics card needs 150W from the PCI Express 2.0 slot, would the 75W PCI express slot still run it? (Maybe take the power from the PSU instead?)
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up vote 4 down vote accepted

The PCI Express bus does not power the graphics card over that amount, it requires a discrete connector from the power supply of the computer. The GTX 550 you linked to does require a discrete 6 or 8 pin PCIe power connector. So long as your power supply is adequate for the new graphics card, you should be able to drop the new card in without problems.

Assuming you have no extra (read: many hard drives or upgraded CPU coolers or overclocking) components, you should be fine even with a power supply as low as 500W. Note, however, that since you're upgrading an older (4+ years) system with a brand new card, you might hit a bottleneck in performance due to the older CPU/memory components.

TL,DR: Make sure your PSU has a 6 or 8 pin PCIe power connector. That new card will require a discrete connection to the power supply, and can not be powered from just the motherboard. Also make sure your PSU is scaled properly for the increased load.

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The card you linked contains a 6-pin auxiliary power socket, which will allow it to draw extra power directly from the PSU.

However, this card is rated at 400W, which means it will need nearly 325W from the 6-pin connector, which might be problematic. Check if your PSU can provide this much power on a single lead and make sure you don't load other stuff on the same 12V output.

Note that running high current on wires not rated for that can generate extreme amount of heat which can melt wires, cause short-circuit and damage your hardware!!

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so I'm going to need a new psu cause mines only 375, i can get a 450watt one for about $35 (…) What did you mean by loading other stuff on the 12v? – Saad Aug 16 '11 at 20:55
No, a 450W is definitely not going to be enough. Your mother board and things on it (CPU) will normally consume ~100W of power. Each peripheral (HDD, DVD, etc) uses roughly 10W. So you will need at least 550W I think. Many PSUs now provide two separated 12V output to better power graphics cards, so you may want to devote one of the output to the card alone and not load any HDD, etc on it. – Aug 17 '11 at 23:53

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