Power Supply Upgrade Question

[Jim_S]

Hello All,

This is not a typical questoin. I have been reading all over the place for an answer with no avail. I have the HP Pavilion A1560n which comes with a 300W power supply. As most of you know, HP uses ATX power supplies and hence for me to upgrade the original power supply, I need to know whether the power upgrade need to be for the 12V voltage rail or the 5V voltage rail. You are probably asking the reason behind upgrading and it is because I have many more hard drives and DVD RW drives that I need to use in this system. Think of this system as a mini server station (albeit not the best system for this) if you will.

With hard drives, one would think that the new power supply should have higher power on the 12V rail. One would argue that an ATX V2.3 is also a good choice here since it has more than one 12V rail and backwards compatible with ATX. However, the fact that 2 different HP technicians mentioned that what I need to upgrade is the power on 5V rail had perplexed me. A third tech just told me that I need more power from the 12V Every power supply that I have come across has more power on the 12V rail except for couple that had the same amount of power from the 12V as my original supply and a lot more power from the 5V and the 3.3V rails.

Could you please refer me to any documentation that could shed some light into which route to go? Should I get an ATX upgrade which would increase the power on the 5V and 3.3V rails or ATX V2.x which will increase the power on the 12V rail.

Thank you

Jim

[erico]

It really is not so complex. Buy a mainstream beast of a PSU with 600-700w. Choose a mainstream brand like Corsair, OCZ. Buy the newer model and you will have all the power you need. High end PSUs have more power on both the 5v and 12v rails. some have dual rails and that is best. Modular is less hassle. For future upgrading look for 80 plus,  EPS12v and PCI-e connectors. Read up on the subject here where many PSUs are compared.

[Jim_S]

Hi Erico,

Thank you for yoru response. I am glad that this is not complex, however my budget is limited to 500W and almost all supplies at that wattage range have either 12V with increased power or 5V. I am yet to come across one that has both slightly increased.

With that being said, you still have not answered the question on which rail needs more power. Your solution was a trivial one but does not help given the budget limitation I have. If you know about which rail would require more power for the upgrade, please let me know.

Thank you again for your response.

[RoyalSerpent · Accepted solution]

You want cheap?  How about $45 for a 600W Fortron with 80+ cert?  Was $35 yesterday with a $10 OFF coupon.  This unit is rate at 580W for 12V ouput.  No need to worry about the 3.3 and 5V rails with modern PC since the maximum load will be less than 100W.  This unit does not have any cross load problem...meaning the system can pull as little as a few watts on the 3.3 and 5V rails, and still be able to deliver close to 600W of total output.  You can purchase adaptor to convert Molex to SATA connector, or vice versa if you have a lot of HDD. 

This PSU has three 12V rails, each rated up to 18A.  Let's say that we stay conservative and de-rate the rating to 16A per rail, one call still load up each rail with eight hard drives.  The CPU and motherboard sit on the other 12V rail and you can put a high-end GPU plus a few more hard drives on the 3rd rail.

The skill level of HP tech can vary significantly.  Great people don't work cheap, so if you want good advice, then you should post these questions at hardware enthusiast forum.

Let's take a specific example for illustration.  I have a WD 1TB green drive on my test bench.  The label said 0.70A @ 5VDC (3.5W) and 0.55A @ 12VDC (6.6W).  Eight hard drives would put about 28W load on the 5V rail and 53W load on the 12V rail.  Double this amount if you want a beefy margin of safety.

Your PC will probably draw about 180W peak due to the older Intel CPU.  I doubt that you will have any problem running six hard drives on that PC with the stock PSU.

http://www.newegg.com/Product/Product.aspx?nm_mc=AFC-&cm_mmc=AFC--_-NA-_-NA-_-NA&Item=N82E1681734101...

[Jim_S]

Thank you very much for your elaborate and informative response.. Kudos!

[RoyalSerpent]

Glad to help.