Pc Freezes playing or no !

[DuoSiciliano]

Hi Guys, I've recently bought a new pc.
This are the specs :
MotherBoard : Asus P7P55D
Processor : QuadCore Intel Core i7 860 , 3051MHz(22x139)
Graphic Card : Asus ENGTS250 1G
Operating System : Microsoft Windows 7 Professional (32 bit)
RAM : 4 GB ( 2GB x 2 )
Power Units : Enermax 500 Watt / Active PFC 100 - 240 VAC

Well , the problem is that i get a freeze everwhere(sometimes(rarely) It works fine) , while I'm playing , at the start at windows logo , on the desktop.
The screen just freezes (sometimes it goes into a black screen) and I have to power off the pc.

The first VGA for this pc was an ATI RADEON HD 4880(with 2 auxiliary power cables) and I had this freezes , so I tried a new VGA and I bought a ASUS ENGT240 1 Gb ( withouth any auxiliary power cable) and I had no freezes , so I tought it was a ATI Driver causing the problem and I bought this Asus ENGTS250 1GB(with 1 auxiliary power cable) and again I'm getting this freezes again.

Now Is it possible that is the Power units that cannot handle this Grapic Cards or anything u could know ?
Please help me guys !

[irishron]

I would say your power supply is too small. Read the specs on your cards, especially the 12volt and get a power supply that exceeds it.

[DuoSiciliano]

So thank you irishron

So , on the box of the grapich card it says :

Power Unit at least 450 Watt (with power current 12V to 24A)

On the power unit it says :
Fuse rating :F10A/250V
DC outpost +3.3V + 5V +12V1 +12V2 -12V +5Vsb

24A 24A 24A 24A 0.6A 3A

130W 456W(38A) 7.2W 15W

Total Power 500W

Do I have to change the Power Unit ?

Thank u very much !

[irishron]

I can't find the power load for your cards but 24 amp seems too low. 450watt power supply for those cards is low end. If you want to play with those cards, get a 750w or larger.

[karamazovmm]

the 4890 or 4870 dunno, use much more power than 24amp, try more than 30amps
the gt 240 shouldn't give you any problems, but a 500w is too low depending if you overclock your cpu, and if your cpu is too powerful... too close to the limit
the gts 250 is the same as the 8800 GT so the consume is very close too the 24amp limit

and enermax is a very low quality psu manufacturer. for psus I don't go cheap, never. Since those things can get into your next build most probably, I had one that lasted me for 3 builds/reforms