Do Older Power Supplies Support Modern CPUs?

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jim evans

I am thinking upgrading an AMD based box. I can't remember the CPU model name
but it's based on the AMD equivalent of a Pentium II and runs on 450MHz. I have
read things that suggest modern CPUs/motherboards require a better quality
power supply.

My question is, can I use the existing power supply in this old box to run a
modern AMD processor (2400) and SOYO motherboard without expecting problems?

jim
 
jim said:
I am thinking upgrading an AMD based box. I can't remember the CPU model name
but it's based on the AMD equivalent of a Pentium II and runs on 450MHz. I have
read things that suggest modern CPUs/motherboards require a better quality
power supply.

My question is, can I use the existing power supply in this old box to run a
modern AMD processor (2400) and SOYO motherboard without expecting problems?

jim
Click to expand...

What's the power supply rated at that you want to use?

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The newer processors depend on the 3.3v and they are sensitive to unstable
supply of power. P4/XP processors are power hungry. If you add in a newer
powe supply with 128 Meg of memory and a cooler, the soundcard and the video
card can use almost as much power as the CPU.

A P4 motherboard needs a special 4 pin plug to be used on the motherboard.
This is one thing to think about for P4 Systems.

If you want to use a SATA hard drive you need special power plugs for the
SATA drive. Some SATA drives may have both types of power plugs. SATA
drives are a big waste of money to me. When they make a motherboard that
uses only SATA buy one. Until then forget it.

For people that have 1 hard drive and one CD computer systems, 300 Watts is
about right. If you like extra lights and multiple hard drives, Multiple cd
cdr/w dvd, and extra fans, and high end video cards then you may need a 450,
480, 550 watt power supply.

I say if a power supply is over 2 years old buy a new one and use the old
one as a backup.If you have a power supply for an old AT style motherboard
like a P2/P3 motherboard it is probably just junk.

Special Features:
A plug to plug into the motherboard to monitor the power supply fan.

Some power supplys have fans that can be controlled by heat or through a
variable speed control.

There is an Antec 550 watt power supply that allows you to adjust the
voltage on the different voltage lines through 5.5" bay panel.

I would purchase a power supply wisely. I think Antec makes very quiet,
extremely stable, power supplies. Some factors to consider is the DBA
(Noise level), how much heat it creates, and how stable the power is that
they create. On the dark side, there is the factor of whether the power
supply supplies the power that the manufacturer rates it at and can handle
the load it claims. Some power supplies have bad reputations like Deer, for
destroying equipment.
 
I am thinking upgrading an AMD based box. I can't remember the CPU model
name
but it's based on the AMD equivalent of a Pentium II and runs on 450MHz.
I have
read things that suggest modern CPUs/motherboards require a better
quality
power supply.

My question is, can I use the existing power supply in this old box to
run a
modern AMD processor (2400) and SOYO motherboard without expecting
problems?

jim
Click to expand...

Too many variables to answer this definitively.
Is your mobo super7 or socket7, with an at or atx psu.
A K6II-450 on a super7 in an Atx box could conceivably have a 250w PSU,
which can conceivably run a basic modern AMD processor with a newer mobo
with minimal devices.
Advice --- buy a new case, even an inexpensive box and psu will bring you
further into the 21rst century.

HTH

Garry.
 
If it's only 250w or not ATX, then yes. If it's 300w ATX, then maybe. You
can try it and see what the voltage readouts are. If they're within spec.
and don't fluctuate much it's ok unless it turns out to be one of those
cheap ones that blow under heavy load, taking some components with it.

The voltage readouts are in the motherboard bios, and better yet, use the
motherboard's software to see what they are during computing.

If they're not too good, then I'd replace it right away, especially if one
or more are down more than 5% from their nominal rating, and flitting lower.

Just replaced my generic 300w with an Antec 300w for $40 (newegg.com, usa).
 
iTsMeMa said:
Too many variables to answer this definitively.
Is your mobo super7 or socket7, with an at or atx psu.
A K6II-450 on a super7 in an Atx box could conceivably have a 250w PSU,
which can conceivably run a basic modern AMD processor with a newer mobo
with minimal devices.
Advice --- buy a new case,
Click to expand...

Or just buy a quality PSU and use the same case, assuming ATX...
even an inexpensive box and psu will bring
you further into the 21rst century.

HTH

Garry.
Click to expand...


--

Are you registered as a bone marrow donor? You regenerate what you
donate. You are offered the chance to donate only if you match a person
on the recipient list. Call your local Red Cross and ask about
registering to be a bone marrow donor.

spam trap: replace shyah_right! with hotmail when replying
 
Or just buy a quality PSU and use the same case, assuming ATX...
Click to expand...


A new PSU in an older ATX case is not necessarily the right answer.
Older ATX cases typically did not have provisions for a rear exhaust fan.

Just my thoughts,

Garry
 
iTsMeMa said:
A new PSU in an older ATX case is not necessarily the right answer.
Older ATX cases typically did not have provisions for a rear exhaust fan.
Click to expand...

I've yet to see this, but it might be the case. Best for the OP to take
a look at his and see. I have seen many new ATX cases have one (or
rarely two) 60mm rear exhaust fan mounts, which is silly IMO unless you
have installed an ear shatteringly loud 60mm fan to move anywhere near
the air that a quiet 80mm one will. I'd buy a good Antec PSU before
buying a new case+psu combo unless, of course, you're buying an Antec
case+psu combo...the PSUs that typically come with cases tend to be
pretty mediocre at BEST :-( And a good PSU will also move a lot of air
out of the case, especially if it has two fans.

Ari


--

Are you registered as a bone marrow donor? You regenerate what you
donate. You are offered the chance to donate only if you match a person
on the recipient list. Call your local Red Cross and ask about
registering to be a bone marrow donor.

spam trap: replace shyah_right! with hotmail when replying
 
spodosaurus said:
And a good PSU will also move a lot of air
out of the case, especially if it has two fans.
Click to expand...

I recently had to replace my generic psu. First I got a Thermaltake dual-fan
psu. Sent it back because the voltages were too out of spec. But the bottom
fan was blowing hot air out the back, creating a hot spot at the top of the
case and frying the CDRW. It was a quiet model, and really didn't move much
air at all. Not compared to my Vantec Stealth 80mm case fans, which move
less than normal too.

Now I have an Antec single-fan psu. It's a quiet model, and moves so little
air that I'm really thinking of putting a Vantec Stealth in there on a 12v
line from outside the psu.
 
I am thinking upgrading an AMD based box. I can't remember the CPU model name
but it's based on the AMD equivalent of a Pentium II and runs on 450MHz. I have
read things that suggest modern CPUs/motherboards require a better quality
power supply.

My question is, can I use the existing power supply in this old box to run a
modern AMD processor (2400) and SOYO motherboard without expecting problems?
Click to expand...

Thanks for all the comments. You have convinced me I should get a new
power supply. My current ATX case has provision for two extra fans
on the back so I'll keep it.

I probably should post the following as another thread and if I don't
get replies here I'll do that.

Another issue that comes up is the video card. It's an STB Velocity
128 8MB AGP 1x. http://www.d128.com/reviews/velocity.html

This machine will not be used for games. So the only question is will
this video card slow the apparent performance of the machine at
routine tasks.

jim
 
Ed Light said:
Huge power supply test today at Anandtech:

http://www.anandtech.com/showdoc.html?i=1841&p=1
Click to expand...

A test that should not be the predominant basis of anyone's buying
decisions.

The supplies were 330-550W models, but Anandtech applied only 300W, at
most, in contrast to www.silentpcreview.com and www.tomshardware.com ,
which apply full rated loads or even more to the supplies they test.

Another problem is the "interference" test, where they tried to
determine the amount of interference generated by the supply by
writing to the memory and then testing the written contents 6 hours
later to find errors. It appears that they tested each computer over
an 18-hour period, running 3 different passes, but there's no way to
know if any variations were caused by temperature (power supplies were
mounted inside the case and could have made the memory run at
different temeperatures), AC line voltage or interference (no
filtered, regulated AC supply was used), electrical noise on the
output lines (no ripple or noise measurements were taken -- what
Anandtech referred to as "noise" is just DC voltage variation,
probably from load changes), or RF emissions (no field strength meter
and spectrum analyzer, despite Anandtech claiming that the Enermax
supplies were the most heavily shielded -- how did they know without
measuring the effectiveness of the shielding?). Anandtech isn't
exactly a shoestring operation, and even if it didn't have all the
needed test equipment, it should have enough contacts to be able to
borrow it. Or at least they could have checked for interference by
using AM and FM radios, TVs, and cordless phones.

About a 420W Turbolink supply, Anandtech wrote:

"The TurboLink 420's specifications struck us as
incredibly poor. Most noticeable is the 185W combined
rail specification. This is actually under the 200W
+5V specification so essentially, this TurboLink 420W
is never capable of obtaining the listed output."

This is outright absurd because at least one of those power ratings
had to be wrong, yet Anandtech ran no tests of its own to verify them
(or the ratings of any of the supplies).
 
Ed said:
I thought they were backwards compatible?
Click to expand...

Different voltages. Newer motherboards are AGP 8x at 1.5V, as is AGP
4x. AGP 1x and 2x were 3.3V. Some cards that were 2x/4x could be used
in both the 1.5V and 3.3V AGP slots. It's unlikely that an old AGP 1x
which needs 3.3V will function in a AGP 8x 1.5V slot.

Ari

--

Are you registered as a bone marrow donor? You regenerate what you
donate. You are offered the chance to donate only if you match a person
on the recipient list. Call your local Red Cross and ask about
registering to be a bone marrow donor.

spam trap: replace shyah_right! with hotmail when replying
 
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