[Solved] Upgraded Power Supply Unit now No POST

Hey guys!

Yesterday I received a couple of parts to upgrade my desktop computer... the main reason im upgrading is because I need better graphics and video encoding speeds.

My computer is an HP Pavillion a6720y... http://h10025.www1.hp.com/ewfrf/wc [...] 856272#N35

Specs: Phenom X4 9550, 6GB RAM, 640 GB Hard Drive, 300W Power Supply

The motherboard has plenty of space for a nice graphics card... But I knew I would need a better PSU in order to get a decent graphics card running properly. So these are the parts I bought:

HD 6770 Video Card - 1GB, GDDR5, PCI-Express 2.1 (x16)... http://www.tigerdirect.com/applica [...] P-_-03ship
Apevia ATX-WA750W Warlock 750-Watt ATX Power Supply... http://www.tigerdirect.com/applica [...] P-_-03ship

This is where it gets weird.. Since I usually work in steps, I decided to get the PSU working first so I could then work with the graphics.

I replaced the PSU, connected all the cables how they suppose to be... I noticed there wasn't a 4 pin molex in my motherboard cpu but realized it wasn't necessary since it had a 20+4 cable instead of the stock 20 pin..
When I turned it on... the power light goes on, fans start spinning, dvd drive works... opens and closes, cpu fans spin for about 10 seconds or so... then stops. and no monitor signal or post... I also don't get any beeps aswell.

Assuming it could be the monitor, tried on another monitor, didn't work either.

So I switched back to the original PSU and that one doesn't work anymore... The power button just blinks and goes off again.

So I tried the Warlock 750W psu on another HP m8200n machine, and it doesn't work either. Although that machine does boot and post when I use the original PSU..

This is the funny part, when I tried using the m8200n's PSU on the a6720y, it does the same as the original PSU, just blinks and nothing... no post.

As of now, there is no way I can get post on my original machine!

Things I've tried":

1) replacing memory
2) clearing CMOS
3) switching back and forth between original and new parts (changing cables)
4) tried the PSU on two diff units - it turns on and seems to be working, but no POST.
5) cleaning case
6) turning the desktop on with no memory, hd, or optical drives - no post.
7) holding power button on with power cable disconnected.

I have no more clues of what to do, any help greatly appreciated

Thank you!

I believe the white 4-pin socket to the lower left of the CPU socket needs 12v power.

http://www.newegg.com/Product/Prod [...] 6812200459

Thanks beenthere!

I was really suspiscious of not plugging that 4-pin...
I will pass by microcenter today and look for it, as I don't want to wait for shipping.

Just out of curiosity tho, how can I have one PSU that works on my m8200n but DOES NOT work on the a6720y? I say this, because the stock PSU for the m8200n does have the old 20pin and the 4pin but when I tried that on my main box, still no post!

Yes, the connector splits in 2 and either side is compatible with the 4 pin socket

As delluser1 indicated use the 4 pin (1/2 of the 8 Pin) the two havles are identical, so does not matter which half is used .
What the difference is that for CPUs with a 125/135 watt requirements the 8 pin connection is need for CPUs with lower power requirements you only need the 4 pin connection. New PSUs come configured so that both the 4 and the 8 pin connection can be made.

I would HIGHLY recommend you reconsider that PSU. A quick search, did not see a review. Did find this.
http://www.overclock.net/power-sup [...] ating.html
You will note that it is "RED" which indicates - DON'T buy.
Have a feeling that that PSU is more suiable for a door stop than in a computer.
Unless you plan on adding a 2nd 6770 GPU a "good" 500->650 W PSU is plenty.
If fact a good 450 would probably work fine. My I5-750 with a 6770 only draws about 300 Watts.

Corsair is a pretty good one that is often on sale at newegg. But which ever PSU you pick look for a 80 or Higher rating for eff. and google the psu an look at a review.

Poor quality psu's often only provide about 60% of rated poor and fail more often which could inturn wip out your MB, or GP, or CPU, OR ALL the above.

It tuns out my PSU was faulty. So I followed Chiefs advice and got a Corsair gs600.

Booted flawlessly! I did have to format Windows since it would reboot on the loading screen.. figured it was because of the new PSU and graphics card... so reformatted and everything works perfect!