For the memory issue, the first thing to do is "reseat" the memory.  Reseat - with the PC powered off, remove each memory module and then reinstall making sure it's fully and correctly seated.  Power on and try.  If you still get a memory error, power off and then remove all but one memory module and then power on and try.  If it's OK, one of the other modules is bad.  If it still shows a memory error power off and try one of the other memory modules.

As far as which brand is less reliable, I do part-time work on PC's and I find other brands have failure rates or problems comparable to Dell's. 

I have found the bad module. I take it there is nothing i can do to repair it?

Will the performance be affected without it?

As i was writing this i tried the pc with the bad module in and it works again.:emotion-40:

Anyway, now i'm back with X300XT BIOS P/N 113-A33437-102 and lights 1 2 3.

Any ideas?

Rgds

For the 9150, lights 123 are "another failure" or in other words ????

First thing is to reseat everything.  All the cables, the memory and any plug in cards such as Video or Sound.   

Have done. Sometimes it gives me the option of safe mode and it works. Then when i start it normally it works for a bit and then crashes again.

Hope its not a write off.

Many Dell's have diagnostics on the hard drive, accessed by F12 at power on.  If yours has the diagnostics run an extended diagnostic (or the diagnostic several times) to see if a problem component surfaces.  As it's intermittent it may take running diagnostics for an extended period before something potentially will show up. 

Related to The Dilema. My computer turns on only when I plug in my power supply, when it does turn on, the system diagnostic lights in the back start flashing random light sequences. I don't know what's going on. then it stops at this diagnostic light sequence.

G=Green

Y=Yellow

G,Y,Y,G

Then Beeps once and then turns off. And i can't manually turn it on again until I unplug it, then plug it back in again after 10 seconds.

The monitor doesn't even show up the loading screen! Plz help

Related to The Dilema. My computer turns on only when I plug in my power supply, when it does turn on, the system diagnostic lights in the back start flashing random light sequences. I don't know what's going on. then it stops at this diagnostic light sequence. G=Green Y=Yellow G,Y,Y,G Then Beeps once and then turns off. And i can't manually turn it on again until I unplug it, then plug it back in again after 10 seconds. The monitor doesn't even show up the loading screen! Plz help

 Despero6

Do you have a Dimension 9150?

If not, what is your computer model and the version of windows that's installed?

Bev.

It just goes straight to the error message even when i hold f12.

I wish i knew what the message was saying. The x300 sounds like graphics card?

Despoero6, it would be better to start a new thread with your problem rather than hijack this thread.

I wonder if the hard drive is the problem.  Disconnect the hard drive and try to boot up.  Obviously Windows won't load, but see if the power on appears to work OK and you can access the BIOS OK.