- Joined
- Feb 13, 2001
- Location
- Twin Cities
Page 1
I see a lot of people discussing the fact that their +5V is low and suspecting that their power supply is the culprit. Some times this is the case, but many times it is not. I will try to explain what I have observed regarding this problem. I have tried to keep it simple and in a context that non-technical people can follow. This is at the sacrifice of some technical accuracy. Those of you into Electronic Academia, look away.
First a small bit of electronics theory. Ohms law tells us that for a given amount of current passing through a resistive path, a given amount of voltage drop will occur. We usually think of copper as a good conductor. Any conductor, regardless of the material will exhibit some resistance to current flow. Obviously, the lower the resistance, the better.
The +5V coming from your PSU goes through a path comprised of several resistances that occur in the different parts of the path. Some are material resistance, like that mentioned above and some are resistance incurred as a result of insufficient contact area.
First, lets look at how the +5V is distributed from the PSU. Some of the conductors go off to the Molex connectors associated with disk drives and some go off to the ATX connector that plugs into your motherboard. Regardless of where they end up, they all originate from a common point inside your PSU. The voltage at that point is sensed by the regulator circuitry in the PSU and is used to control it at a (hopefully) fixed level.
I see a lot of people discussing the fact that their +5V is low and suspecting that their power supply is the culprit. Some times this is the case, but many times it is not. I will try to explain what I have observed regarding this problem. I have tried to keep it simple and in a context that non-technical people can follow. This is at the sacrifice of some technical accuracy. Those of you into Electronic Academia, look away.
First a small bit of electronics theory. Ohms law tells us that for a given amount of current passing through a resistive path, a given amount of voltage drop will occur. We usually think of copper as a good conductor. Any conductor, regardless of the material will exhibit some resistance to current flow. Obviously, the lower the resistance, the better.
The +5V coming from your PSU goes through a path comprised of several resistances that occur in the different parts of the path. Some are material resistance, like that mentioned above and some are resistance incurred as a result of insufficient contact area.
First, lets look at how the +5V is distributed from the PSU. Some of the conductors go off to the Molex connectors associated with disk drives and some go off to the ATX connector that plugs into your motherboard. Regardless of where they end up, they all originate from a common point inside your PSU. The voltage at that point is sensed by the regulator circuitry in the PSU and is used to control it at a (hopefully) fixed level.
Last edited: