|"I am told this is an issue with the pcs power supply which is 300watts. The card packaging says it requires at least 350 watts."|
When I search using: HD 5550 system requirements watt
, most of the "hits" say 400 watts minimum, but a few say you can get by with less - 350 watts maybe but not likely 300 watts.
When I search using: HD 2400 or HD 2400 Pro system requirements watt
, most of the "hits" say 300 watts minimum.
When I search using: HD 2400 XT system requirements watt
, most of the "hits" say 350 watts minimum.
"I have noticed that once the card is reinstalled I dont have the issue for a few hours and then it returns.When I put back the old 2400 card ther is no issues at all. "
That probably indicates your power supply is inadequate, and is being constantly overloaded when the HD 5550 is installed. In that case, the card often works fine at first, but eventually the PS at least overheats, and it will be damaged in the longer term.
The 350 or 400 watt requirement is one of two requirements - the other is the PS must be able to supply at least a minimum current (amperage) at +12v. Some 300 watt PSs may be able to supply enough current, but the +12v max amperage rating varies considerably for the same wattage capacity, and it appears your power supply is probably inadequate in that regard.
Your power supply must have at least the minimum capacity required to support a system with the graphics card you are using installed, or the max graphics card you might install in the future.
(Onboard video - video built into the mboard - IS NOT A CARD ! )
If that info is not in the ad for the video card, you can go to the video card maker's web site and look up the specs for the model - often under system requirements - the minimum PS wattage, and, more important, the minimum amperage the PS must supply at 12v is stated. If you don't find that, any card with the same video chipset including any letters after the model number has very similar minimum PS requirements. Some power supplies have two or more +12v ratings - in that case, add those ratings to determine the total +12v current capacity.
If you're a gamer...
In most if not all cases, the max capacity rating of the PS is an intermittent rating. It's recommended that you do not load your PS to any more that 80% of that rating if you are going to be using something that puts a constant load on it, such as playing a recent game for hours on end. In that case, you multiply the min capacity stated for the system with the particular video chipset on the card by 1.25 to find the min. capacity of the PS you should get.
If you need to get a PS with more capacity, you can usually replace it with any decent quality standard sized standard ATX PS.
Standard (PS/2) power supply size - 86mm high, 150mm wide, 140mm deep, or 3 3/8" h x 5 7/8" w x 5 1/2" d , or very close to that, though the depth can be more or less for some PSs.
Don't buy an el-cheapo (in quality) PS.
See response 3 in this: