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PSU Suggestion

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August 28, 2012 12:00:28 PM

I'm confused as to choose a new PSU for my PC. In fact I don't even know if I need one; when running my PSU does not get noticeably hot, and my Bstc unit worked for about 10 years before before I replaced it (perhaps without good reason !)

It has been suggested that I do need a more highly rated PSU to solve a failure-to-boot on very high proportion of the time. My PC frequently does not boot, the screen remains totally black, but the power sees to be there as the LEDs on every disk in the system flash at least once, USB power is present, and the CPU fan spins rapidly (PSU fan also is working) (On the small fraction of times it does boot the CPU fan starts only when the CPU has reached 60C).

The Bestec PSU which I removed (250W)[suspected but not proven defective] has the following current ratings:
+3.3V +5V +12V -12V 5Vsb
18A 25A 14A 0.8A 2.0A(2.5Amax)
and the Octigen one with which I replaced it has the following:
+3.3V +5V +12V -12V -5V 5Vsb
16A 20A 12A 1A 0.3A 2.0A
with additional restrictions on the power drawn from certain combinations of rails for both.

I have a 20 pin main board connector, a 4 pin "P4" connector (also on motherboard), the 3 x 4pin-in-line Molex connectors on my disks, and one floppy disk 4-pin mini power connnector in use. My PC has 6 USB sockets, I might use 4 or 5 at once (kb/mouse wireless, Modem, camera, printer, external H disks, flash drive, joystick, etc). The other specs are as below.

My system is quite old, and thus I fear it draws a higher proportion of the current it needs from the +5V and +3.3V supplies than from the +12V supply compared to newer systems, which makes some newer systems perhaps under specified for my system (I take as the required current specifications to be at least than of the Bestec above). Also, the trend to SATA and towards 24 pin connectors means that some PSU's don't come with the necessary connectors (I know that it's possible to to 'make' more connectors by 1-n way splitters).

I'm looking at a ~500W unit ? which meets the above requirements (but I am willing to adjust my minimum specs in the face of a reasoned argument), which would give the reassurance of sgnificantly more current than I need (by perhaps 25% ?). I've used the eXteme Power (lite) power calculator, which indicates a minimum power of ~300W and at worst case ~450W (when I include the PCI wireless network card not yet installed).

I don't really understand the multi-12V rail situation either; if you have 2 12V rails each rated at 20A, that means to me something won't work properly if it needs more than 20A at 12V, but I think that's irrelevant for my system seeing as >17A at 12V is significantly more than I've ever had.

I am aware that most people will make the general recommendation to buy a recognised brand, and there must be some such PSUs which may be appropriate, but many do not have the right combination of connectors or do do not have capacity on the lower voltage rails (which a lot of the cheaper, 'non-recommended branded' PSUs do have if one believes their spec); another consideration, perhaps is the value of my 11 year old rig compared to the cost of any new PSU !

So, to conclude, anyone have any suggestions or recommendations for suitable PSUs for me bearing in mind the above considerations and further info. below ?

Doh
28.August.2012
Compaq Presario S5160UK DT261A under XP/SP3 Home edition
Processor - Celeron 2.7 GHz (Northwood I think)
Motherboard - MSI MS-6577 v2.1
RAM - 1GB + 512MB (1GB +1GB max) DDR PC2700
PSU - Octigen 300W model 10270PSOTG ('upgraded' from original Bestec 250W PSU [in 2011?])
Nvidia GeForce 6200 graphics card in AGP slot.
56K modem in PCI slot

More about : psu suggestion

a b ) Power supply
August 28, 2012 4:17:53 PM

Quote:
my Bstc unit worked for about 10 years before before I replaced it (perhaps without good reason !)
Did you replace it to resolve the failure to boot issue? A 300W PSU should be fine for that system. Unless you added components to it, the PC doesn't draw more power now than it did when new.
August 28, 2012 10:02:31 PM

Thanks for your response.

I can't remember, but no I don't think so I didn't replace it because of the particular issue I alluded to. Yes I have added componts to the original system as detailed below, to make it up to what I have now.

The reason I replaced the original Bestec PSU was because something was playing up, I can't remember what, may well have been a boot problem. The LED/Green light on the back of the Bestec PSU was blinking a a number of times and from the HP troubleshooting instructions I deduced, correctly or mistakenly, that the PSU had gone wrong in some fashion. I did try to test the PSU (unloaded) with a DVM and the voltages all looked OK.
I replaced it with a slightly higher power one anyway, the Octigen 300W unit.
You will have noticed that the current ratings for the individual voltages are all lower than for the Bestec original.

A few years before that I had installed an Nvidia GeForce 6200 graphics card in the AGP slot, and before that upgraded memory from original 256MB to 758MB (1 DIMM -> 2 DIMMs) ; even more recently I replaced the 256MB DIMM with the correct 1GB DIMM from Kingston, making total RAM 1.5GB. The analysis programs showed memory present and correct, as does Windows Task Manager.

The reason why I am thinking of upgrading my PSU at the current time is that when I have described the failure-to-boot problem, one thing that was suggested (twice) was an underpowered PSU. The eXteme Power Supply calculator suggests ~300W for a minimum and when I enter maximum configuration I get ~450W !

Doh
28.August.2012
Compaq Presario S5160UK DT261A under XP/SP3 Home edition
Processor - Celeron 2.7 GHz (Northwood I think)
Motherboard - MSI MS-6577 v2.1
RAM - 1GB + 512MB (1GB +1GB max) DDR PC2700
PSU - Octigen 300W model 10270PSOTG ('upgraded' from original Bestec 250W PSU [in 2011?])
Nvidia GeForce 6200 graphics card in AGP slot.
56K modem in PCI slot.

Related resources
August 29, 2012 8:39:52 AM

GhislainG said:
A quality PSU like the Antec EarthWatts Green EA-380D should meet your requirements: http://www.newegg.com/Product/Product.aspx?Item=N82E168...

You could also get a more powerful PSU like the Rosewill Green Series RG630-S12 630W: http://www.newegg.com/Product/Product.aspx?Item=N82E168..., etc.


Thanks a lot Ghislaine.

I had seen the Antec EarthWatts series and was even considering the EA500 model, but even that has a rated output at +5V of 24A, compared with the original Bestec's of 25A (it's a -12Z REV C not the "lemon" described on jonnyGURU's website which was an old -12E, hopefully my version has better 5Vsb circuitry: it came in an HP [Compaq] machine, and I had pretty high opinion of that company once), but more than the 20A "regulation" that I'm using now.

I've read a few reviews now, not only the one on jonnyGURU of the Bestec ATX-250-12E, I now doubt the specs given for current ratings on ANY PSU - perhaps that's why Corsair don't give any on their website.

I have never heard of Rosewill, but maybe they only trade in US and I am in the UK (hence also it's not worth Newegg shipping items to me).

What's "OCP Set Point" ? (used on the Antec website)

Doh
29.August.2012
Compaq Presario S5160UK DT261A under XP/SP3 Home edition
Processor - Celeron 2.7 GHz (Northwood I think)
Motherboard - MSI MS-6577 v2.1
RAM - 1GB + 512MB (1GB +1GB max) DDR PC2700
PSU - Octigen 300W model 10270PSOTG ('upgraded' from original Bestec 250W PSU [in 2011?])
Nvidia GeForce 6200 graphics card in AGP slot.
56K modem in PCI slot
a c 158 ) Power supply
August 29, 2012 11:56:58 AM

OCP is Overcurrent Protection setpoint...the PSU shut downwhen it draws that amount of power on the specified rail(s). Do you still have the old Bestec unit? If so, then I'd throw it in the PC and see if it resolves your fail to boot issues. Based on the specs of the Bestec and the Octigen, I'd say the Bestec is the better PSU....and is sufficient for your PC.
a b ) Power supply
August 29, 2012 12:14:16 PM

Quote:
I had seen the Antec EarthWatts series and was even considering the EA500 model, but even that has a rated output at +5V of 24A, compared with the original Bestec's of 25A (it's a -12Z REV C not the "lemon" described on jonnyGURU's website which was an old -12E, hopefully my version has better 5Vsb circuitry: it came in an HP [Compaq] machine, and I had pretty high opinion of that company once), but more than the 20A "regulation" that I'm using now.
Don't forget that newer PCs don't need a lot of current on the +5v rail. The +12v rail is far more important. If you want high +5v current (why?), then you'll have to find a PSU with an older design, e.g., the COOLMAX CA-400 400W which I definitely wouldn't recommend. Stop worrying about the +5v rail and buy a quality and efficient PSU.
August 29, 2012 4:18:17 PM

Rugger said:
OCP is Overcurrent Protection setpoint...the PSU shut downwhen it draws that amount of power on the specified rail(s). Do you still have the old Bestec unit? If so, then I'd throw it in the PC and see if it resolves your fail to boot issues. Based on the specs of the Bestec and the Octigen, I'd say the Bestec is the better PSU....and is sufficient for your PC.


I don't understand....perhaps it's the terminology...if the rail is rated at 20A (or whatever) how can the PSU deliver 34A (the OCP) on that rail before it shuts down ? Surely you'd want the OCP to be rated limit ?

Yes I still have the old Bestec unit. I might just give it give it a try. The eXtreme Power supply calculator reckons I need at least 300W to run my system. If I disconnect eevrything except the graphics card, 1 usb for k/b & mouse, and the HD it still has the same problem.

But that PC (spec below) has other problems right now...I tried Start>Restart and now the screen says "Windows is shutting down" (that was as far as it got)...it still says that now, 4 hours later....wondering what to do...

Doh
29.August.2012
Compaq Presario S5160UK DT261A under XP/SP3 Home edition
Processor - Celeron 2.7 GHz (Northwood I think)
Motherboard - MSI MS-6577 v2.1
RAM - 1GB + 512MB (1GB +1GB max) DDR PC2700
PSU - Octigen 300W model 10270PSOTG ('upgraded' from original Bestec 250W PSU [in 2011?])
Nvidia GeForce 6200 graphics card in AGP slot.
56K modem in PCI slot
August 29, 2012 4:50:59 PM

GhislainG said:
Quote:
I had seen the Antec EarthWatts series and was even considering the EA500 model, but even that has a rated output at +5V of 24A, compared with the original Bestec's of 25A (it's a -12Z REV C not the "lemon" described on jonnyGURU's website which was an old -12E, hopefully my version has better 5Vsb circuitry: it came in an HP [Compaq] machine, and I had pretty high opinion of that company once), but more than the 20A "regulation" that I'm using now.
Don't forget that newer PCs don't need a lot of current on the +5v rail. The +12v rail is far more important. If you want high +5v current (why?), then you'll have to find a PSU with an older design, e.g., the COOLMAX CA-400 400W which I definitely wouldn't recommend. Stop worrying about the +5v rail and buy a quality and efficient PSU.


I hadn't forgotten that, thank you for stressing that point. I obviously did not make myself clear: the PC was purchased in 2001 (almost 2000) and so it is not a newer PC. Thus the frequently stated comment that the really important thing is the is the current available on the +12V rail(s) may not be applicable to my PC, and my PC may have a different requirement in terms of the distribution of currents between the low voltage rails (+3.3V and +5V) and the +12V rail(s) to that required for state-of-art PCs.

Therefore I took as the worst case (my minimum spec) the spec for my original Bestec unit, assuming, perhaps rashly, the designers at Compaq were competent. This is one consideration in how I arrived at my new requirement. It is only recently that I became aware that there was more to choosing a PSU than the total power - X amps at Y volts MEANS to me at least X amps at Y volts for the lifetime of the PSU, not X amps at at significantly less than Y volts for some transient period, hence my mistake with the lower rated Octigen PSU. I was also unaware of my misinterpration of how the manufacturers quote the performance of their PSUs compared to how well (some of) them perform in fact (reading some detailed reviews).

Therefore at present I feel that the current available at +5V is important for my PC (I hope I have explained the reasons for this), although I would like to be convinced that this was not so

Doh
29.August.2012
Compaq Presario S5160UK DT261A under XP/SP3 Home edition
Processor - Celeron 2.7 GHz (Northwood I think)
Motherboard - MSI MS-6577 v2.1
RAM - 1GB + 512MB (1GB +1GB max) DDR PC2700
PSU - Octigen 300W model 10270PSOTG ('upgraded' from original Bestec 250W PSU [in 2011?])
Nvidia GeForce 6200 graphics card in AGP slot.
56K modem in PCI slot
a b ) Power supply
August 29, 2012 5:30:51 PM

Back in 2001, PSUs were designed with more emphasis on the +3.3/5v rail than the 12v rail. Believe me the Antec EarthWatts Green EA-380D ($37) exceeds your PC's requirements for all voltages. The 3.3v and 5v combined output is 115 W. If it fails to boot with that PSU, then the problem is somewhere else (most likely the motherboard). If you feel that such a PSU isn't powerful enough, the CORSAIR Professional Series CMPSU-650HX at $125 will definitely meet your +5v requirements (30A).
a c 158 ) Power supply
August 29, 2012 5:31:36 PM

The big OEMs are usually pretty good about figuring out power requirements and getting a PSU that is more than sufficient in the PC. They're also pretty good about getting good quality PSUs...they figured out a long time ago that it's easier to sell good quality than it is to have unhappy customers and lots of customer support issues.

Hanging on shutdown in XP usually means that the OS has gotten bloated or corrupted. When was the last time the PC had a fresh OS load? I found myself formatting the HDD and reloading XP every 3-5 years. This isn't causing your fail to boot issues, but could help overall performance...when you get the PC running.

I just noticed that you upgraded to the Octigen in 2011...so the system was running stable for a year or so before you started experiencing the fail to boots symptoms?
!