Power supply need a 600+ watt power supply for my gateway gt5656 computer. is that possible?

Yes. Exactly. You have found the problem.

http://support.gateway.com/s/pc/R/1009371/1009371nv.shtml

Uses an ATX form factor Power Supply. One that is common in a LOT of desktop computers. Readily available.

Gateway Support indicates there are three generic Power Supply makers, for the Power Supply in your computer,
Delta, HiPro, and Bestec. (Same one's for HP too)

Indicates the form factor is uATX/BTX.
Whatever, Gateway.

An ATX Power Supply's case dimensions are approximately -
6 Inches Wide, 5.5 Inches Long, and 3.5 Inches Tall.

Power cabling is also a designator when referring to ATX.
The new Power Supply's on the market, cover ATX power cabling, and more.

This is an example of an economical, yet reliable, Power Supply, that will work,

http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=4465483&CatId=1079

Has all the power cables you will need, plus more. Tie the unused power cables up out of the way. (USE plastic ties)
Concerned it is a 500 Watt unit, and not a 300 Watt unit as came with your computer?

No need to be.
1) A computer ONLY uses the power it needs, and NO more.
If you are surfing the internet, and the computer only needs a 100 Watts, it will ONLY use 100 Watts.

Playing an intensive game, or using an intensive program?
Could use the whole 500 Watts.

2) Will it harm your computer? No.
You could use a 10,000 Watt Power Supply, and it won't harm your computer. (10,000 Watt is an exaggeration)
Why?
Because a computer will ONLY use the power it needs, and NO more.

For additional questions please post in a Comment.
Regards,
joecoolvette

Gateway Support > Gateway DX4860 series of Desktop PC's > Main Support page,

http://support.gateway.com/us/en/product/default.aspx?tab=1&modelId=3696

On this page click on the User Guides tab.

(Drivers, BIOS, Applications, Patches, Support Documents, Top Answers, User Guides)

Then on Generic User Guide.

Other than that you may be referring to a MOTHERBOARD MANUAL. Not available, however;

http://support.gateway.com/us/en/s/desktop/2011/gateway/dx4860/DX4860nv.shtml

Click on Specifications;

1) All the Processor options listed, use the same processor socket;
the LGA 1155,

http://en.wikipedia.org/wiki/LGA_1155

2) Motherboard has an Intel H67 motherboard chipset,

http://en.wikipedia.org/wiki/List_of_Intel_chipsets#Core_i_Series_chipsets

http://www.hardwaresecrets.com/article/Inside-the-Intel-Sandy-Bridge-Microarchitecture/1161

C) Ram Memory;
Up to 16GB's of DDR3 Sdram, that operates at a frequency rate ('Speed'), of 1333MegaHertz.

http://www.hardwaresecrets.com/article/Inside-Intel-Nehalem-Microarchitecture/535

4GB ram memory modules ('Stick') in the four ram memory slots, is 16GB.

However NOT a good idea.

With the Nehalem architecture you NEED to use 3 ram memory modules, (The Sandy Bridge architecture is an evolution of the Nehalem architecture),

http://www.hardwaresecrets.com/article/Inside-Intel-Nehalem-Microarchitecture/535/2

From the above,

"The memory controller integrated on Nehalem-based processors, provides three memory channels, i.e., it is capable of accessing three memory modules at the same time, IN PARALLEL, in order to improve performance.

In THEORY triple-channel architecture provides a 50 PERCENT increase of available bandwidth, compared to a dual channel architecture running at the same clock rate."

The above is from Gabriel Torres, author.

From me;
Note the words used, "In THEORY".

From extensive testing by another website, it was found long ago, that dual channel architecture does NOT increase ram memory performance by much.

THEORY was that using two LIKE ram memory modules, would increase ram memory performance up to 30 PERCENT.

From extensive testing, (MANY motherboards, processors, and ram memory modules), and another website, it was found the actual increase is more like ONE to TWO percent.

THEORY.

In otherwords looks good on PAPER.

(Be aware that Gabriel knows it is theory also. That is why it is stated as T-H-E-O-R-Y. Gabriel is VERY INTELLIGENT. The theory stated is from Intel, not Gabriel.
Gabriel, as I do also, knows it is just ON PAPER. Doesn't really work that way in reality)

Read on down through the article from this intelligent person, and you will find out more, about why you should use THREE ram memory modules, in comparison to using FOUR, in all four ram memory module slots.
{ Luv ya Gabriel! You are THE tech! }

D) Graphics: Intel HD Graphics,

http://en.wikipedia.org/wiki/Intel_HD_Graphics

Since all of the Intel Core i processors listed, use the Sandy Bridge architecture, the Intel HD Graphics, is HD Graphics 2000,
(DESKTOP processors),

http://en.wikipedia.org/wiki/Comparison_of_Intel_graphics_processing_units#Intel_HD_Graphics

It's just Integrated Graphics, anyway.
(Integrated graphics is also known as OnBoard graphics.
ON the motherBOARD)

There is a PCI-Express x16 expansion slot, however.
A PCI-Express graphics card can be used.

TWO things;
1) I would use a PCI-Express 2.0 graphics card, and not a PCI-Express 2.1, or 3.0 graphics card.

2) The Power Supply is 300 Watts. BETTER, to bump it up to an economical, reliable 600 Watt unit, { It is an ATX unit }, if you are going to use a graphics card.

{ Does indicate 500 Watts full power, but this is FULL power, and may also be another option, than the 300 Watt Non-PFC unit.
A different power supply, option.

It is better to have a power supply, that can put out at LEAST 10 percent more power, than what is needed. Power supply lasts longer as it doesn't have to strain }

Just ONE example,

http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=899124&CatId=1483

{Be aware that a computer will ONLY use the power it needs, and NO MORE. Just because you have a 600 Watt power supply, does NOT mean the computer will use 600 Watts all of the time.

Surfing the internet? About 100 Watts.
Playing an intensive game? 600 Watts }

For additional questions please post in a Comment.

Regards,
joecoolvette

You may have a motherboard problem - check the BIOS battery first and then re-seat the CPU and RAMs.

The load is one thing, like how many watts does it supply. You'll want that or higher in the new one. Just as important though is what is the new power supply compatible with. Some name brand machines made theirs with unique dimensions so that only theirs would fit in the case... If you have a standard size case, then you're probably good to go. Look at the plug for it, there are two bundles of cables in some, and the plug type. If possible, checkout the tech specs on the model on the Gateway website and that should give you the basic info you need for searching on a replacement.

:o)

the power supply wattage rating is MAX wattage, not constant wattage. the power supply only outputs the amount of power that the rest of the computer calls for, and no more. if yor computer only needs 200 watts, that is all that will be sent from the power supply; even if it has a max rating of 600 watts, it will only send the amount of watts which your computer calls for.

Hello,

You can replace the pc with the same watt power supply or upgrade to around 420W and still be able to run your system within thermal threshold. The power supply should be a 20-pin ATX power supply.

Good Luck
C2Solutions

One of two Power supply setups came with the system

103108 - 300 WATT HIPRO Power Supply
103941 - 400-Watt Power Supply

They should like you back to gateway also

Here you go. You can get drivers and manuals for it.
http://support.gateway.com/s/PC/R/1015002R/1015002Rnv.shtml

This power supply has an odd form factor so just "any" power supply won't work.