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Graphics card upgrade leads to power supply issue

Hi there, thanks beforehand for this amazing service. Appreciate your help!

I've been tackling a graphics-card issue for about a month now. The nutshell version: I run Windows XP SP3 on a Dell XPS400 that's 5 years old. Recently my original graphics card (nVidia GeForce 7900) died on me so I went to the store for some shopping. My machine has a 375watt power supply so I grabbed a relatively inexpensive replacement card that had a low enough wattage (300w) -- the EVGA nVidia GeForce GT430.

Upon removing the old card and installing the new one in the same slot, I noticed that the old card had a 6-pin mole connector that went right to the power supply whereas the new card had no such plug. So I stowed the now-unused power cord in a corner of the unit and got the new card going.

Here's where the problem started: everything seemed to work fine, the video appeared, the drivers installed smoothly (including new drivers from the web). But then when I tried watching a video (Hulu, Youtube, Netflix, etc.), sound crackling would be mixed in with the audio. I've never had a crackling issue on my computer before. The crackling would happen whether through my speakers or through headphones I inserted into the front of the machine. I have a Creative Soundblaster x-Fi Platinum, model SB0460, which sits a couple inches away from the video card and came original with the computer.

I speculated that MAYBE the reason for the sound issue had to do with the way the new card didn't use that 6-pin connector. Maybe the connector provided grounding to the old video card that was lacking in the new one, thus making it emit more electrical interference to the sound card? Maybe the power suck from both the new video card and the Soundblaster card together on the motherboard was causing it? All I knew was, the more intricate the video images on the screen, or the bigger I made the window, the more the crackling happened. So, to test my theory, I went back to the store and bought a new card that would use the 6-pin connector like the old one. This card, also EVGA, was the GTS450.

Lo and behold -- the crackling has gone away!! Problem appears to be solved! It's been a couple weeks so I'm guardedly optimistic. But, as sometimes happens, you fix one thing and another problem arises. It appears that since my computer was originally built, video cards (and perhaps motherboards?) have come far enough along that any card with a low-enought wattage to match my machine (300w or 350w for instance) no longer needs that 6-pin connector! Across the board, there don't seem to be any "<350w" cards with the 6-pin connector to the power supply. The new card I got, the GTS450, was the lowest-wattage such card I could find, and it.... is 400 watts. :-(

I'm wondering, just how much of a risk am I running with this 400w card on my 375w system? I've read comments here and there on the web that Dell machines have underrated power supplies and can actually handle more than they say. Thoughts on this?

1) What is the worst thing that could happen? Should I upgrade the power supply to be safe? And if I do,

2) Will that lead to other upgrades I then have to do to keep everything compatible? I'm just wondering how far this chain reaction leads on an older system like mine... or is the power supply a relatively independent element that won't require me to update other parts as well.

Appreciate any assistance on this issue! It is way beyond my level of knowledge on computers! Thank you!
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  1. Best answer
    Manufacturers power reccomendations are for the entire system and are bloated to make up for the low quality psu's that are on the market.
    Most of the power required by your card and the rest of the system comes from the 12v rail.
    The Dell makes most of it's 375 watts available to the 12v rail ( 30a / 360w )
    This gives it basically the same useable power as many 400- 450 watt power supplies.
    Shouldn't be anything for you to worry about.
    If the psu does fail ( it happens ) it can be replaced with almost any standard ATX unit.
  2. Thank you! That's a reassuring explanation. I'm wondering, if worst-case scenario the PSU does fail, what kind of risk do I run from that incident? Could it fry my motherboard?

    Also, I'd be curious to get your quick take on the issue I had with the sound crackling and how I ended up addressing it. Have you heard of this before? Does it make sense that my approach (getting the card that needed the 6-pin connector) solved the issue?

  3. You're welcome.
    Even with the best power supplies there's a risk ( much lower, but still there ), I've yet to see a Dell psu take out a motherboard though.
    The sound issue is wierd, personally I'd blame the card, having seen dozens of them go bad.
    I've got one in a drawer somewhere, still works, next chance I get I'll try and recreate the issue.
  4. Cool, thanks again for your help.
  5. Best answer selected by sumojoe.
  6. This topic has been closed by Mousemonkey
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