New power supply = disk boot failure?

I have a one year old refurbished HP m8100n, that has been working excellent with the stock 300w PSU. However, I'm going to upgrade from my current 8600GT to a 8800GT, and I fear my 300w PSU won't have enough juice.

So I've bought a 430w PSU that many has had their 8800GT powered with. No the new 430w PSU is not dead, it powers everything up when I boot up my system.

However, after the blue HP pavilion screen, instead of the usual Windows loading bar screen, a black screen with the following message appears: "Boot disk failure. Insert system disk and press ENTER."

So I figured it must be my cables not being plugged in all the way. I replugged the only four things that needed to be plugged, the 4-pin peripheral power connector to my hard drive, a 5-pin S-ATA connector to my hard drive, the 24-pin main connector*** to my mobo, and the 4-pin +12V power connector to my mobo. Still, that message showed up.

Then I thought it must be that my disk boot really failed. So I took off my 430w PSU and put back my old stock 300w PSU, plugged everything back in, and booted it up. Well what do you know? Everything ran fine again.

So here's what I eliminated as the problems:
-PSU NOT DEAD. I repeat, PSU NOT DEAD.
-Everything plugged in correctly.
-Boot disk is fine and intact. If only with the stock PSU.

And yes, both my CD / DVD drives are empty.

***There WAS however, one suspicious inconsistency. My mobo has a 24-pin slot, HOWEVER, my stock PSU has only 23-pins, with an empty pin in the middle of the 24 slots. The 430w PSU has all 24-pins filled. What is the meaning of this? Is this the cause of disk-boot failure?

Power supply color codes

Red +5
Orange +3.3
Black Ground
Yellow +12

Get your volt meter out and check the voltages.
You have to have the 24pin pluged in the the MB, Push start button, take voltage readings use chart above. Dont check the 24pin connector while it is plugged in. To check the 24pin connector you have to jump 2 pins and I dont remember which 2. Just google it.

It looks like kaitanuva bought an older ATX PSU instead of an ATX 2.2 PSU where pin 20 is not used (-5V no longer is required). An ATX 2.2 PSU should resolve the issue.

well if you don't have a volt meter then you have no way of knowing if the power supply is bad or not. the pin combination may and i say be the issue. with brand name pcs its really hard to do upgrades on them because some are the parts are very exotic. the mobo's in brand name computers are custom made by the usual mobo makers so you might want to try to find the make and model of the mobo in your PC and see if you can find some specs on it

Your HP PSU is ATX 2.2. The Thermaltake that you bought is rather old (ATX 1.1) which also explains why it's so inexpensive. I have one of those that was bought several years ago for a P4 2.8 PC which still works fine with it.

See [url=http://itwinkle.stores.yahoo.net/beathp3024ps.html][/url] for the specifications of the HP PSU. If you compare the specs, you'll see that the 300W PSU from HP is as good as your new Thermaltake PSU.

The wattage (300W vs 430W) is meaningless, particularly when looking at older PSUs. Just check the amps for each voltage:

HP
+12V 19.0A
-12V 0.8A
+5V 30A
+5VSB 2.0A
+3.3V 28 A

TR2
+12V@18A
-12V@0.8A
+5V@30A
+5VSB@2A
+3.3V@20A

Based on the above, how can you be convinced that the Thermaltake is better?

It's the other way around. Your HP PSU doesn't have pin 20 (-5V) and the motherboard definitely doesn't need it.

See http://www.formfactors.org/develop [...] atx2_2.pdf (figure 8 - Main Power Connector) for the ATX 2.2 specs. As you can see, pin 20 is identified as NC (No Connection). While -5V could be provided, but few ATX 2.2 PSUs do.

The Thermaltake either is not compatible (most likely) or it's defective. Since it's not even as good as the original HP PSU, why even bother with it? Most people get a new PSU to get more amps on the 12V rails, not to get less. You should have bought a PSU that has two 12V@18A or more, not a single 18A rail.

That's a good PSU and it should work.

+12V1@17A
+12V2@17A (408W total on the +12V rail)
-12V@0.8A
+5V@24A (less than the HP, but should be enough)
+5VSB@2.5A
+3.3V@24A (also less than the HP, but should be enough)

That cooler master psu is horrible, get this one: http://www.newegg.com/Product/Prod [...] 20cx%20430