Six beeps at post and no joy with boot up

clear CMOS.

POST ("power on self test") codes for the Dell GX280 are in a format of n-n-n as in 3-1-2. This would sound like 3 beeps, followed by 1 beep and finally 2 beeps. If you're not paying attention, that 3-1-2 beep code could sound like 6 simple beeps.

Dell has a page for the GX280 dedicated to Troubleshooting Tools and Utilities. There's a great deal of information on it - but the POST codes you're looking for are explained in detail about mid-way down under "Beep Codes" This document and associated links should go a long way to help you properly diagnose the problem with your GX280.

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sounds like a PSU problem check all electrical connections that attach to your hard drive including IDE,SATA leads or simply replace them all and new PSU i would personally recomend you get a heavy duty PSU with plenty of wattage from problems that i have had you can bid and win on Ebay $30 PSU as i did
hope this helps

Confirm no leaking or bulging capacitors on your mothboard.
refer to here
http://en.wikipedia.org/wiki/Capacitor_plague

As this was a common problem with the GX280.
If found, you will need to replace the capacitors.

The other check is to make sure the heatsink is fitted correctly, perhaps reaply the thermal paste if you have any. I know that high temps would switch the GX280 off.

system halted my pc help

Hello,
Look at this article, (scroll until the down page), you will find a table of beeps and their meanings : http://en.kioskea.net/pc/bios.php3
Hope this will help you.
Best regards.

Tap the F8 key when booting up. This brings you to a screen with different options. Choose Use last known good configuration. this should solve the problem. Your system is stuck in a loop.

Please don't forget to rate me.

According to the Dell website your board has a 16X PCI express graphics slot. If so, you can ask for any PCI express graphics card at your retailer. The memory size and performance of the card will depend on your budget.
Hope you find this info helpful.

The bios beeps indicate bad memory
http://www.amptron.com/html/bios.beepcodes.html