Sapphire R9 280X Dual-X And Psu

Thank all of you!
I need at least 600-650w, but i maybe I get a 750w just to be 100% sure.
What PSU's do you suggest?

thanx for your answer! I know i have read some stories about RMA these kind of cards, 290, 280x but in most cases there were flickerings and other crashes... your case is similar with mine. But I hope it is the psu..Thermaltake tr2, doesnt provide enough A to feed this card in its 12v rails...I would buy a new psu anyway, not only for this card.. I chose this: http://www.eteknix.com/xfx-pro-750w-black-edition-fully-modular-power-supply-review/

So i will install it later days and i will see. If problem happens again , then I will RMA. For Now i will try to set cpu at stock settings just to test. Thanx anyway.

well.. i underclocked cpu at stock, and i removed secondd hdd and dvd-rom and crash happened again.. 2 times. At second time i had no blank screen, sound crashed too..

According to Event viewer i have this info:
Log Name: System
Source: Microsoft-Windows-Kernel-Power
Date: 3/9/2014 5:28:27 PM
Event ID: 41
Task Category: (63)
Level: Critical
Keywords: (2)
User: SYSTEM
Computer: Home
Description:
The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly.
Event Xml:
<Event xmlns="">
<System>
<Provider Name="Microsoft-Windows-Kernel-Power" Guid="{331C3B3A-2005-44C2-AC5E-77220C37D6B4}" />
<EventID>41</EventID>
<Version>3</Version>
<Level>1</Level>
<Task>63</Task>
<Opcode>0</Opcode>
<Keywords>0x8000000000000002</Keywords>
<TimeCreated SystemTime="2014-03-09T15:28:27.938140000Z" />
<EventRecordID>5892</EventRecordID>
<Correlation />
<Execution ProcessID="4" ThreadID="8" />
<Channel>System</Channel>
<Computer>Home</Computer>
<Security UserID="S-1-5-18" />
</System>
<EventData>
<Data Name="BugcheckCode">0</Data>
<Data Name="BugcheckParameter1">0x0</Data>
<Data Name="BugcheckParameter2">0x0</Data>
<Data Name="BugcheckParameter3">0x0</Data>
<Data Name="BugcheckParameter4">0x0</Data>
<Data Name="SleepInProgress">0</Data>
<Data Name="PowerButtonTimestamp">0</Data>
<Data Name="BootAppStatus">0</Data>
</EventData>
</Event>

I googled and after reading microsoft support site about this event I suppose it is more likely to be a power supply problem..

I am on this scenario:

" Scenario 3: The system randomly restarts and no Stop error BugcheckCode is listed, or the computer is completely unresponsive (hard hang)

Click here to show/hide scenario
The Stop error code and the PowerButtonTimestamp are listed as zero. For example, consider the following scenarios:
The Stop error BugcheckCode value is listed as zero. Circumstances can prevent writing the Stop error BugcheckCode information before the computer restarts or shuts down. In this case, a BugcheckCode value of zero is logged. Also, perhaps no Stop error occurred, and the shutdown resulted from a power loss. For example, on a portable computer, this could mean that the battery is removed or completely drained. Or, on a desktop computer, this could mean that the computer was unplugged, or a power outage occurred.
The PowerButtonTimestamp is listed as zero. Circumstances can prevent writing the PowerButtonTimestamp information before the computer restarts or shuts down. In this case, a value of zero is logged. This can occur if the power button is pressed and held for at least four seconds when Windows has an operation running that prevents writing the event to disk. You might also see this scenario if the computer is “hard-locked” and therefore unresponsive to any input, and the computer has to be powered off. To determine whether the computer is unresponsive, try pressing the CAPS LOCK key to toggle the CAPS light on the keyboard.
To check whether this scenario is occurring, press the CAPS LOCK key on the keyboard. When you do this, if the CAPS LOCK light on the keyboard does not change when you press the CAPS LOCK key, the computer may be completely unresponsive (hard hang).

This scenario usually indicates a problem with the hardware. To help isolate the problem, check the following items:
Overclocking: Disable overclocking to see whether the issue occurs when the system is run at the correct speed.
Check the memory: Verify the memory by using a memory checker. Verify that each memory chip is the same speed and that it is configured correctly in the system.
Power supply: Make sure that the power supply has enough wattage to appropriately handle the installed devices. If you added memory, installed a newer processor, installed additional drives, or added external devices, such devices can require more energy than the current power supply can provide consistently.
Overheating: Check whether the system is overheating by examining the internal temperature of the hardware.
Defaults: Reset the system back to the system defaults to see whether the issues occur when the system is running in its default configuration. "

Any info/opinion would be useful , Thanx in advance

I finally took XFX 750w psu(it runs fine until now) and I have the same problem with black screen In Assassins creed Liberation which I tested. I also have this problem when running furmark stress test and try to launch gpu-z after that. 80% of times I do It, system crash with black screen.. :/ .. I also saw that core clocks dont stay at 1020 constantly they drop to 870 and then go to 1020 again while gpu stressing.. I am thinking to go to the shop i bought to get another card but I dont know If they can find the problem cause it is on specific games and in the case of gpu z and furmark.. I also made a ticket to sapphire support after registering my product, explaining them my situation and waiting for their answer. :/

Yes..I dont know if it is normal or not.. maybe it is normal , I dont know, cause it is happening with furmark, maybe it is a part of the test. As i remember it doesnt happen in games, but i am not 100% sure, I will check again.

As for my issues, Sapphire finally answered me. They told me to contact reseller for hardware check and RMA.( i explained everyhting exactly)

I also would like to ask you, was RMA easy? It is the first time I will do it. how many time it took you to get the new card. .What brand it was

I wish it will be like that for me, too... Sapphire already told me to get the card to the store for hardware check/rma. Does it mean that they will give me a new card? Or there is a case that they just test it and give it back to me saying that is ok.. also , what brand was the 290? sapphire? just for the info.