AMD crashing problem with new build

I am slowly driving myself insane with my new build.

These are the specs:

AMD x2 5000+ Black Ed.http://www.tigerdirect.com/applica [...] -AM2-5000B

500w Ultra LS500 PSU http://www.tigerdirect.com/applica [...] =ULT-LS500

2gb of OCZ ram http://www.tigerdirect.com/applica [...] =O261-8070

a PNY Nvidia 9800gtx video card http://www.tigerdirect.com/applica [...] u=P56-9802

an Asus M2N-MX mobo http://www.tigerdirect.com/applica [...] =A455-2810

with a seagate 250gb sata drive http://www.tigerdirect.com/applica [...] 50AS7%20SY

this rig is also running on vista sp1

Now the thing runs a bit hot about 40-45 (it ran hotter with my pos heatsink) celsius at idle, and for the longest time I have been thinking that my crashing issues have been related to heat, although after changing out my heatsink, I don't believe that to be the culprit. It only crashes during heavy CPU load (IE playing Oblivion or CoD4) I could practically set my watch to it crashing in CoD4. I have relentlessly checked to see if it was my Video Card having a conflict with vista, no dice, I have done a fresh install of Vista, no change, I turned on OS plug-n-play and stangely enough I seems to atleast stall it. I am quickly running out of ideas. I have a feeling It could be my PSU but on paper It should (atleast I think) support this rig, the only other thing that it has to power is my DVD drive.

I have been surfing these forums for a while now trying to find an answer to my problem and have now just caved in and decided to make this post.

I was wondering if anyone else has had any similar issues/ideas as to what could be causing this?

I hate to rule out anything, but I currently think my PSU is causing this. I am also probably going to pick up another 120mm fan for it as well, even If I am no longer certain that heat is causing the crashing I am sure I couldn't hurt.

Also While I am here I am noticing that my core temps have a pretty big gap between them presently I have core 1 at 45 degrees and core 2 at 28 degrees. I am not quite as up on dual core processors As I probably should be so is that normal? or should I be looking for a way to correct that? I have been reading about bad temp sensors with this specifc CPU.

If you got this far thanks for reading the mindless rantings of a frustrated mad man, and let me know If you have any ideas for my problem.

Firstly are you overclocking?
Are these Temps from within windows whilst under stress?
Use a windows temp reading program, not bios.
Try to run the vista scoring thing? Tests GFX card and pc, and directx etc...

I THINK, PLUG AND PLAY SHOULD BE ON BEFORE YOU INSTALLED IT NOT AFTER, CAUSE IT WAS INSTALLED WITHOUT PLUG AND PLAY??

You can Check RAM with memtest386, but i doubt thats ur problem unless your overclocking that?
Else, Ebay sells PSU testers cheap, dunno what they are like though.
Also Check with your motherboard manufacturer for BIOS updates for your board

Well, you said it is crashing during a heavy CPU load, but is that only during gaming?

Run Prime95 to get the GPU out of the loop.

Run memtest as another person said.

If memory fails, try swapping them out. IE. Take the one out of the second slot, and test again. If it still fails, put the one you took out back in, and remove from slot A. If it still fails, it would either be bad memory or motherboard.

Check your power output. Is it within specs?

Have you tried to check eventvwr.msc to see if it could lead you in a general direction?

Let us know, we are all happy to help.

running prime 95 right now, ran memory test and it passed, gonna post results in a sec

I dunno about the unevenness of the core temps, but those temps don't seem awful if they are at load 59 is a bit high to me on that core tho, also the stock hsf isn't so bad, mine were 31 and 38 on my 5400 under load. You have a black edition which is basically a higher "bin" chip, it may be running close to it's limits, thus generating more heat vs a chip with more breathing room (afaik anyhow ). maybe reseat your hsf ?

A minimum 500W or greater system power supply (with 12V current rating of 26A)

Above was quoted from the spec page for the 9800gtx...
I would also assum that your problem is the power supply you have. I would think you shoud go with a cosair 600 to 650..

I STAND CORRECTED< SORRY I WAS WRONG

Each 12 volt rail needs to be 24Amp minimum for the 9800 GTX, sorry i was mistaken earlier.

No it can't be added like that, not without rewireing and your better off, geting a better one.
But if it says 20 thats not enough.

The 280 gtx requires the 32Amp.

Basically higher AMPS = better cause you can upgrade your card later.

Should say on a sticker on the PSU.
12V - XXAMPS
12V - XXAMPS
ETC

I have since notice that this products pages are being removed all ova the internet, By the sounds of it you bought a dud model or brand.
Pays to buy a decent PSU!