Annoying Persistent 5870 no boot problem

I Have written in before about this but the problem keeps coming back after being fixed temporarily.

Currently my build is:

Intel i7 860 2.80GHz
Asus P7P55D-E Pro Mobo
8GB (4x2) Corsair XMS DDR3 1600MHz ram
XFX Radeon HD 5870
Asus Xonar D2X sound card
Anthena power 950 watt
1TB WD Caviar Green HDD (upgrading after this problem is fixed)
Samsung DVD burner
LG Blu-ray burner

Win 7 64

My problem is that when I try to boot most of the time The PCIe/VGA LED on my mobo stays on and I get no display and no boot. Sometimes I get the beep code for no detection too. NOTE: my nvidia 9400 works fine no matter what.

I had a similar problem with my last mobo, but it gave me the AMIBIOS code '2A' the rest of the configurationw as the same

Things I have tried
-Driver sweeping ALL drivers. This usually works for a little while until I turn off power at the PSU and then I can't boot next time I try. I also don't understand why this is fixing a problem with booting up at times.
-Clean install. When driver sweeper doesnt work this has.
-I also worked and am working with XFX
--I RMAed a first 5870 which worked for them and they sent back and now I am getting the same problem
-all combinations of sticks of ram I could work out from each one on its own to all 4. it seems to have no effect on whether it boots or not.
-tried with card in both possible slots

I havent been able to replicate these results in a systematic way but sometimes it seems to boot better with the HDMI monitor not plugged in.

I have replicated the mother problem on 2 diff motherboards with cards XFX assured my worked in their labs, so it much be something else.

When my computer works it works great and I love it.

I have posted a topic on this before as I thought it was fixed, however I thought I would post an updated concise version of the problem.

If I can provide any more information please let me know.


I did find these two threads that talk about an issue very very similar, my fan sometimes hits 100% . I thought i'd include them in case anyone was interested.

http://www.tomshardware.com/forum/276815-33-radeon-5870...
http://www.tomshardware.co.uk/forum/forum2.php?config=t...

my only question is that if it is the PSU as some of these folk have suggested how would I know what a good one to replace mine with would be?