I have a Dell Dimension 4700 service tag D6KFG61 I want to know if the power supply will work with a new motherbors I bought ? I bought a new motherbord from TigerDirect that is a e-7050/610i geforce shocket 775.
Never post your service tag here or on the Dell forum. Not needed... Ever !
The 305 watter you have is the mean average but the peak is higher, but depending on the video card you are going to get, this maybe a time for a new power supply (PSU) to handle not only a new video card but possibly other hardware.
Also, that power supply will not have the power cables to handle some video cards either. A power supply, good one, is one of the most important hardware for your system. Do not skimp on it.
In addition to SR45's comments, that PSU may have a small +12V rail. So whatever you do, I highly recommend buying a new and QUALITY PSU. Please post the rest of your specs or planned upgrades so that we can start recommending PSUs for you.
The PSU is the least problem. It's a standard ATX 12v model, capable of running 115W Prescott CPUs. It was mostly Pentium 3 and older systems that used the non-standard PSU pinouts. I believe that I had also seen an early S423 model, but none of the S478 or later systems used the weird pinouts.
The bigger problem is replacing the motherboard. The stock cooling uses 4 extra mount points on the case to screw down the heatsink through the motherboard. You could dremel those off, or I should say you *must* do something or else your new motherboard would short.
The stock PSU is fine if you're not going to throw a quad core and a decent video card in it. I'd recommend buying a new case though. The airflow in the 2350/2400/3000/4600/4700 case (same case, different front/side panels) is very poor, especially when you'll be giving up the direct CPU exhaust venting.