Defective PSU or mobo?

[AuroEdge]

I have stability problems on a computer I've been looking over. I think it's a power issue however I don't know how to determine if the motherboard or the power supply is inadequate. I'm using a 400W CoolMax power supply and the motherboard is a GVC AR862. With SpeedFan I found the respective voltages for two different CPUs I tested. The Duron was stable for the most part. The various Athlons I swapped in functioned way less than favorably.

Duron 750MHz (rated 1.6V), Idle | 100% Usage
-Core: 1.67V | 1.67V
+3.3V: 3.34V | 3.32V
+5V: 4.98V | 4.95V
+12V: 12.42V | 12.36V

Athlon 1.3GHz (rated 1.7V), Idle | 100% Usage
-Core: 1.77V | 1.92V
+3.3V: 3.36V | 3.34V
+5V: 5.08V | 4.82V
+12V: 12.42V | 12.36V

I think it's a power issue because the motherboard is rated up to 1.3GHz Thunderbird CPUs however it won't even run an Athlon 1.0GHz let alone the 1.3GHz. If this is indeed a power supply issue what brand and wattage is suggested? System has low power video card and only 1GB RAM.

[budz]

test it with a spare power supply before you decide on buying a new one.

[lowellriggsiam]

What kind of stability issues?

[AuroEdge]

What kind of stability issues?

The PC will not boot Linux Live Distros or Windows Install when using 1.3 or 1.0 GHz processors. It also crashes when put under stress when using Prime95 or other CPU intensive applications. The Duron CPU operates well but the various Athlon CPUs I've tried seem to eat up a lot of power and cause unpredictable but definite crashes.

I really don't know much about power supplies. It seems to me that the 12V and 5V rails are important for mobo and CPU operation. 12V seems fine but the 5V suffers when CPU is stressed. I am aware that not all PSUs are made equal but to that end, I don't know what brand and wattage is sufficient. And that's assuming that the motherboard is fine and the power supply isn't.

[lowellriggsiam]

Admitedly that'd drive me nuts if it were my PC. Does the computer abruptly shut off, fans running, hear the hard drives? In my experience seldom is the CPU the issue, unless the CPU fan has stopped functioning and even then you can usually get windows xp to load before it shuts down.

[newpath]

I know little of the motherboard you are testing, so this is just a suggestion. It is likely that neither the motherboard nor the PSU are defective. It is possible, however, that your motherboard is incompatible with Athlon processors you are trying to use, especially the 1.3 GHz model. The GVC AR862 is also known as the GT133KT manufactured by BCM Advanced Research for GVC and used in Micron PCs. Check this page for some details: http://www.bcmcom.com/tech/GT133KT/GT133KT.htm. Note that the processor speed is limited to 1.0 GHz. You might get lucky and find a BIOS upgrade that would allow the faster Athlon to work. As budz suggested, if you have a bigger PSU, you can try it, but I bet it won't do the trick.

Let us know.

[AuroEdge]

I have your same suspicions regarding the GT133KT chipset. The original motherboard in this Millennia PC is a GT133KT and indeed refuses to POST any CPU higher than 1.0GHz. It has stability issues, so when I saw a slightly bulged capacitor I thought maybe the mobo was bad. I got this http://www.centrix-intl.com/details.asp?productid=3841 because it would just be a simple swap. It is also a GT133KT but it does officially support up to 1.3GHz Athlon somehow. The power draw for the 1.3 is a bit less than the 1.0 so that would explain why it does a little less terrible when stressed. Ultimately lockups happen for both.

Interestingly enough, I found a contemporary article that shows 400W PSUs failing to power an Athlon 800MHz whereas 250W and 300W units worked. So, what should I be looking for in the replacement power supply?
http://www.anandtech.com/showdoc.aspx?i=1128&p=15

EDIT: I really like this one. Will probably get it for testage http://www.antec.com/Believe_it/product.php?id=Njg=

[bevills1]

More likely a mobo problem in my experience. I've had 2 different mobos with VIA chipsets and had problems with both. The latest one boots without problem except that it randomly changes boot order, and I may have to reset boot order when I need to boot to CD or floppy; however, there are no other problems besides boot order not retained. I much prefer Nviidia and Intel chipsets and have never had such problems with Nvidia or Intel. Also I've run several systems up to 3400 MHZ on 250 watt power supplies with not problems

[AuroEdge]

More likely a mobo problem in my experience. I've had 2 different mobos with VIA chipsets and had problems with both. The latest one boots without problem except that it randomly changes boot order, and I may have to reset boot order when I need to boot to CD or floppy; however, there are no other problems besides boot order not retained. I much prefer Nviidia and Intel chipsets and have never had such problems with Nvidia or Intel. Also I've run several systems up to 3400 MHZ on 250 watt power supplies with not problems

Agreed. Haven't had an issue with Intel. If only the owner knew 10 years earlier...

I was able to borrow a Dell 250W PSU. With the 1.3GHz, the CoolMax 400W dips down to 4.70V for +5V under load and the Dell 250W drops to 5.00V.

I still had random lockups but they were far less frequent for the 1.0GHz and 1.3GHz. I have a suspicion that memory is an additional factor. The 64MB CL3 PC100 stick that shipped with the PC is fine. I'm trying 256MB and 512MB CL2 PC100 which seem to lockup. Could this be a problem and if so where would be best to find CL3 PC100 512MB RAM?

[bevills1]

You can test memory using memtest to determine if it's bad if you suspect bad memory. About 6 months ago I had 2 of 3 memory sticks test bad which was determined by running memtest with 1 stick at a time in the mobo. I'm unsure what differences are between CL3 and CL2 are, and it could be a problem depending on what the differences are. It's best to go to http://www.crucial.com/?gclid=CJn3sc7F0Z8CFQEhnAodJFeP4A&cpe=pd_google_us&ef_id=1705:3...20100201161934 or other memory site to enter computer or mobo model number to determine correct memory type. Note you don't have to buy Crucial or any particular brand as long as it's the same memory type. You can find various prices for CL3 PC100 at http://www.google.com/search?sourceid=navclient&ie=UTF-8&rlz=1T4ADSA_enUS335US339&q=cl3+pc100+memory for example. At one of the links there I saw 256MB CL3 PC100 for less than $15.

Edit: According to a couple of sites from the Google link CL2 is non ECC while CL3 is ECC, and some mobos require one ECC which might explain the lockups with the non ECC memory if that mobo Requires ECC memory.

[Nelson37]

With a PC that old, I would not recommend spending any cash on upgrades or repairs. It is just not worth it. If somebody brought such a machine to me for repair, it would not even have enough salvage value to justify hauling it away to the dump for free.

I have recently sold two, 3.0Ghz Pcs with licensed XP for $75.00 each. I often give such boxes away for free along with one hour of setup and training for $75.00. Boxes as old as yours go to the side of the road.

[AuroEdge]

I have gotten this sorted out. The 1.0GHz functions correctly. The processor performed better on the borrowed PSU. It provided 5.00volts or better on the +5V rail whereas the PSU in the case drops down to 4.72Volts under load. Is there a seemingly obvious correlation between performance and power being supplied? Thanks for all of the input.