I have built pc cpu e8400 , mbo gigabyte x38 ,2x2gb corsair dhx , 320 wd sata and vga 3870 (i put it in last couse i think its reason of problem).PSU is 450w Chietec , it think is enough (but maybe im wrong and this is couse of shutdown.)When i start pc after 2 second it shotdown and after 2 sec again starts.But every time its shut down when picture on monitor should be (i hear sound that monitor makes when picture is comming).I thinks its something whit graphic card , couse when i remove aditional 6pin power from card and start pc ,normaly i dont have picture but pc dont shutdown .Pc vetns and case vents are running const and pc dont lose power.When i put back additional power for 3870 again same problem.I dont think that chiftec 450w is problem but maybe im wrong.Is it card or low power.Mbo its not problem but maybe it is something with pcie 2.0,but i doubt.When card is in slot but not 6pin in the psu works..Any sugestions welcome

Thanks in advance and sorry for bad english

Dean

Do you have another video card you can use for testing?
I am not familiar with the Chieftec brand of PSU. I would think 450W would be enough, but if the PSU is low quality, it might really only be good for 300W or so, which isn't enough.

its Chieftec (i was writeing fast and f.... it) .Chieftec is solid psu never having problem till now.And i still thinking its not problem.I dont have other card .My old pc on which im posting this has agp.I will try 3870 today on my friends comp.If works than i dont know ....I hope thats nothing with mbo .

Check that the CPU cooler is on correctly, with the proper amount of thermal paste and is making good contact with the CPU. If the CPU is overheating, that could cause the symptoms you describe.

Good Luck!

Clark is probably right, usually if the CPU cooler is not on correctly it will shutdown very quickly without warning or any indication that that is the problem.

Seeing as you built an Intel system their coolers are hard to get in sometimes.

Check the HSF to see if it's seated properly and the fan is plugged in.

Imo, it is the PSU. The PSU you have is not of good quality. A 450W PSU is enough only if it is high quality like the Corsair 450VX.

I suspect that your PSU is inadequate.
1) if you don't power the vga card, you progress further into the boot process.
2) 2 seconds , repeating does not sound like enough time for a cpu to heat up, shutdown, cool off, and repeat.

AMD requires a 450w or greater psu.
http://ati.amd.com/products/Radeon [...] ments.html
They have a list of certified psu's, and chieftec is not on it. In fact, chieftec is not generally recognized as a high quality psu. Under load, or at higher than room temperatures, a lower quality psu will not deliver it's advertised claims. Also, a cheaper psu will not deliver amps on the 12v rail/s where you need it for a vga card. I think the 3870 wants 26a. Look on the chieftec psu label, and tell us what it says. You are looking for the total amps(or wattage) that can be delivered on the 12v rail.

ok but if is cpu should it shutdown even without graphic card.Its shoutdown only when graphic card i powered.I have box cpu with thermal pads allready on.Fan is working all 4 plastic scrows are sitted.I will try card today.

+12v1 14A + 12v2 15A

Sounds like PSU does not have power enough to star the thing up. If You disconnect graphics there is much less power draw on startup and it starts. Cannot tell for sure. If You have another PSU available try that. Otherwise disconnect hdd/cd, case fans, additional cards to lower power draw that might help if You are on the edge of what PSU can deliver. I had one customers PC which did that when added wireless card, first thought that it was compatibility issue, turned out to be too weak PSU. Funny thing was that in one PCI slot it was starting 50% of the time on the other never. With PSU replaced problem was gone.

+1 for the PSU.

I have had a similar problem in the past, but with a X1950 video card. When I plugged the card, PC would start but when the POST screen showed up it restarted automatically in a never ending cycle.

My PSU was a "500W Generic" model, that was running with no major issues an old 6600GT. When I switched to a Hyper 540W SLI Certified PSU the problem disappeared and, in fact, some other small issues that I was having were gone too (some freezes, weird reboots, etc).

If I were you, I would try changing the PSU first, and then move to the video card if that does not work.

PC Power & Cooling 610 is -constant rated- 12 Volts @ 49 Amps and all on one rail so it is 100% usable.
Last price I saw was $109 USD.

Big thanks to all.Great forum and members.
I will try combination with PSU and card .But now im closer that is problem with PSU (12vrail).when i disconect 12vatx for cpu than graphic card works and it works around.In short 12v cpu and 6 pin graphic card connect = shutdown and power up in loop.So i have chance to buy corsair 550vx.On paper it look good and net-reviews are pritty good .What do u think about that corsair.I have e8400+x38mbo+1xsata320+2x2gbddr2corsair+1xdvdrw+2fans120mm.I think that wats are nor problem but what with this 12v rail.I read that this psu has 41A

Go for it. I recommend Corsair and PC Power & Cooling PSUs. Both are top quality PSUs.

It was not PSU.Now i have 650tx corsair and same problem.Also not video card with my friend 2600pro same problem so...
Its official its not graphic card.I tryed with 2600 pro and the same.So

option number:
1) mbo has contact with metal back panel (i check it put mbo out on wooden table and tryed booting but is the same)
2) i read on some forums that heatpipes of mbo sometimes shortcircuit with mbo.(i cant check this.With eye its look ok)
3)hm this could maybe be .also from forums that mbo reboot in loop couse ram.something with voltage .It works with 1.8v but higher reboots something like that.I have corsair 2x2gb dhx 4-4-4-12 2.1v.Maybe this is reason.To solve this i must raise voltage in bios for mem.But i cant go to bios.I will try taking from friend 1.8v memoryThan if it boots change voltage settings and reboot with my memory.

4) try cpu in my freinds pc .By elemination.PSU new 650w corsair good,VGA good if RAM and CPU Good than by by by my x38.Im allready crazy.I had never big problems with any comp till now.

Looks like you have a bad board. RMA the board.

Thanks for helping.I solve the mystery it was MBO.The last thing on my list was dead.Deep down i knowed that is mbo but i dont wanna to believe and try everything.Cheaper GIGABYTE MBO GA-P35C-DS3R works perfect.Streight from box (he he he plug and play.not really small things must be adjust .For some reason cpu was x6 not x9 for 8400.Ram was 5-5-5-17 not 4-4-4-12 for my dhx.Once adjusted no problems after)Im not fan of gigabyte couse bios,but this board works perfect.No problems like need bios update,dont work with 3870ati,dont work with memory nothing,everything works for me.)
12h in work tryed games ,vista instaled ,xp instaled in dual boot.No single crash or glitch for now.
some thoughts about mbo

+
it works from box with factory overclcked memory and new 45n cpus(miracle for 35 chipset)
ddr2+ddr3 support (im not in need for now but nice feature)
Solid build

-
not crossfire (for now not real problem - but who know what future brings)
4pin power 12vcpu (its big board with plenty of unused space and now standard 8pin should be nice)
realtek network im not fan of realtek networks

Once agian thanks for help and sorry about bad english

Glad to see you got it working . As far as my experience goes you are lucky with that board. Most P35C chipset based boards have issues with RAM.