Would you believe it, I finally have enough cash to get my 2nd Radeon HD4870 (1gb), so that I can go crossfire with my original Radeon HD4870 (512mb) set it all up in my Gigabyte X48 - DS4 and all goes fine for an hour or so then nothing. It switches off. No BSOD no warning and I hadn't started to overclock. So I go through the normal Troubleshoot routines until it's 3am and Im down to just the board and my PSU, still it starts up for 5 - 10 seconds then switches off again, comes back on again and so on... I even try a different PSU to rule out that but still the same problem.
The board has been fine since I bought it in May and just went skewwhiff when I installed the two cards, I also installed a new PSU that day a COOLMASTER M700 real power 700watts, but that's working fine and I dont think has any relevance to the Mobo messing up.
Is this a fixable problem? Am I missing something obvious? (I have tried shorting the BIOS) Has someone else has a similar problem or does this mean a trip back to the shop and a battle of wits to get a refund???
So if anyone can shed some light I would be eternally gratefull and here's a "Thank-You" in advance.
The single most common cause of the "on-off" syndrome is failure, in one way or another, of the mechanical thermal interface between the CPU and the HSF (HeatSink/Fan) assembly. The symptom is caused by by the CPU being unable to 'spill' heat to the HSF; thus - power up, get hotter than blazes pretty much instantly, and - poof - thermal trip, shutting 'er down! Was there any kind of untowardly mechanical incident getting the second GPU in? Higher force than expected for insertion, or perhaps, slip of the hand? Wiggling the HSF may sometimes find a problem, but best bet is to actually look at the backside of the board - check that all four pins are in and seated, or locked, and that you don't have a cracked pin or lock...
OMG, Bilbat your a genuis!!! I forgot to mention I upgraded the CPU stock cooler to an ARTIC Cooling Freezer Xtreme, which with the new PSU and extra GPU was a nightmare to fit in (Just not enough space). I finally got them in but must of done something... I COULD KISS YOU.. THANKS.
I have had numerous people swear to me here that they're sure they did the HSF install correctly, and then sheepishly come back to report either a pin loose, unlocked, or cracked... It's not inattention or incompetence, either - there seems to be a contest going on (but I think Intel's system wins hands down with their really crappy 'stock' 775 piece) to see who can design the worst, most impractical way to attach a heatsink! I've tried a few, and, with one exception, they all stank! (The exception: I finally bit the bullet and went to water - have a D-Tek Fuzion, and it came with: an 'x' shaped, threaded, metal backing plate with reinforcing ribs and a molded-on foam rubber insulating pad, and a spring-loaded set of screws with a machined release [not a single &^%$ ^%#@ plastic piece involved!] that lets you get to exactly the correct tension, and then simply turns without tightening further; the drawback - you have to have unimpeded access to the back of the MOBO; I've written D-Tek and told them they should quit wasting their time on water-blocks, and sell mounting systems to every HSF manufacturer!)
IMHO, the best feature of GB's 'ultra-durable' MOBOs (which is, otherwise, a bunch of ditzy marketing hype - '50 degrees C cooler'? - I'm pretty sure that if anything on my MOBO was 50 cooler, there'd be frost forming on it!) is that they'll take enough pressure to get an HSF seated without giving you the ominous feeling that you're a half-ounce of pressure away from a dreadful, fatal snap! Another point to be made is procedure: it's usually easier to 'work your way' around the chip, but, for the best results, you want to do a pair of diagonally opposed pins first, and then finish up with the other two...
And ther you go, a pin cracked and sitting half in half out, you have just saved me a trip down to Tottenham Court Road where i was about to head to head with the shop manager to try and get a refund or at least a swap of mobo!!! Again Bilbat Thank You and keep posting your a life saver (well almost)..
Owe you one..Londonboy.
And just to finish off with a happy ending...I installed the old stock HSF and low and behold the Mobo works like a dream. You were spot on Bilbat and deserve a medal, now all I need is some new pins for an Artic Cooling Freezer xtreme Unit, any suggestion??? Only messing. So in conclusion "Give that man a Job"