Are you sure because the only chipsets that support it are the 945 and 955x chipsets, the 820GM uses i believe neither of those, but a variant of the 915P chipset specifically for BTX chassis. I find that it can be upgraded to dual-core hard to believe. If you have this computer, can you tell me what motherboard you have?
ROger
well, i posted this on another forum and thought you guys might be interested. sry about the pics' links as it was in forum code, but you can still click on them.
Introduction
I had never really been a big computer gamer my whole life. Playing Ages Of Empires was fun and also Command And Conquer games. I wanted to become a pc gamer. I read reviews on Battlefield Vietnam and decided I had to get that game. I built a budget of $1200 and since I didn't want to spend any of that money on games and such, I asked the game for Christmas. I got the game and also Halo. Now, I was gaming on a Sony Vaio with a Pentium 4 1.8GHz, 256MB of RAM, and an upgraded gpu, the 5200. While this sufficed and met requirements for BFV, I got the habit of looking at my FPS and noticing they were not the best, so I decided to look for a new computer.
Build Or Buy?
Where to start? My original plan was getting an Antec P160 and adding a socket 478 P4 to it, but LGA775 was now created. I ventured into Shuttle saying that the G5 with support for PCI Express and LGA775 was the way to go. I loved the style of that pc, it was beautiful. I read countless user reviews and forums on this pc, discovering something that would eventually scare me out of building my own pc. I read that you had to connect a wire from the power supply to the mobo to power the graphics card. It was not in the manual and the thought of doing something wrong scared the crap out of me. So, I moved on. I found Velocity Micro's SX-V. I had configured it to a Pentium 4 3.4GHz with 1GB of RAM and a 6600GT, but the price was alot at $1600. Some may be asking why I wasn't looking at AMD. Being an Intel fan my whole life, i knew I wanted Intel power but that didn't make my decision. I blame PCI Express. When I started shopping for a pc, I read about the new graphics slot and how it was future proof. Well, they had me at future proof. In January, the month I would buy my pc, AMD did NOT have socket 939 motherboards with PCI Express, at least with Velocity Micro they didn't. Then how did I end up with a Gateway after looking at building it myself and looking at Velocity Micro? It still boggles me, but I knew I would NOT buy a dell, I never used one, and read bad things about it. Well, I decided that I didn't have $1600 and was scared of building my own Shuttle, so I checked out BestBuy. I went to a local BestBuy and saw that monster there. The Gateway 820GM, very powerful for it's day and at a great price of $1200. Although there were Sony Vaios there and also HPs, I wanted to try something new, as I saw it featured something called BTX which NO ONE ELSE HAD. It had 2 x 120mm fans, intake and out take, so I charged the $1200 and returned home with it not knowing how really potent this pc really was.
Specs Of This PC
The Original specs were slightly weak, but it was something special.
Intel Pentium 4 530 3GHz (Sadly, the 6xx series didn't arrive before January 3rd)
1GB (2 x 512MB) of PC3200 RAM upgrade able to 4GB
250GB SATA hard drive, room for 3
Dual Layer DVD burner and DVD ROM
Media Card Reader
ATi x300 128MB PCIe GPU
Windows Media Center Edition 2005
At first glance, most gamers say, ''Oh, that is weak''. But I can proove that this is a very Potent PC.
Pictures
http://www.supload.com/thumbs/default/the front.JPG
http://www.supload.com/thumbs/default/my pc_24.JPG
http://www.supload.com/thumbs/default/my pc_1.JPG
http://www.supload.com/thumbs/default/IMG_00126456.JPG
*Note that is not the original power supply.
with the 6600GT
http://www.supload.com/thumbs/default/IMG_03664564.JPG
http://www.supload.com/thumbs/default/IMG_0367-263885.jpg
Setup, Ease Of Use
When I first turned this pc on, it sounded like a jet plane. The two 120mm fans running at full speed is quite loud obviously but the noise winded down to an in audable level. i went through the normal XP setup with out a problem. The speakers it came with were actually OK for my taste, but the keyboard and mouse, I never used as I have a Logitech keyboard and wireless mouse. It ran fast and quiet, but I noticed something wrong. I looked in the back to dicover the read fan not moving. I opened up the case and found the IDE cable blocking it. I moved the cable and the fan started moving. That was my only problem really.
Amazing Upgrade Potential
Now, how to turn this $1200 pc into a gaming pc? Well, the first thing I wanted to do was replace the graphics card. I looked at an ATi x800xl which required a 350w power supply. Mine only had 300w. So, I went to my local Frys and purchased an Antec True 480w for around $120. It installed with no problems as the case uses a standard ATX power supply unlike dell. Months later, I bought a BFG 6600GT instead of an ATi x800xl. I had the money, but I read good things about this card and it doesn't dissapoint. So what's so special about this OEM pc? BTX. It is truely an overclockers dream. I managed to hit- 598/1336 with STOCK cooling for my 6600gt which is amazing. The upgrading is what is also cool. I have asked Gateway about upgrading the CPU and the motherboard and am quite shocked at what I found out. ''The CPUs are upgradeable even to dual core and the 6xx without a BIOS upgrade or any problems.'' The motherrboard? ''As soon as BTX motherboards becomes avaible, you can upgrade to them since it uses a standard BTX mounting and a standard BTX size motherboard.'' I know, it is truely amazing. An OEM pc that can be upgraded to 4GB of memory, a dual core cpu, and even a standard motherboard.
Cooling
The CPU is cooled by the 120mm intake fan hence it has no fan on it's heatsink. It will stay under 60 degrees celcious during gaming while still remaining un hearable. When I use SpeedFan, and have the fans running at a special setting at 1400RPMs, which is still quite, the CPU stays under 55, even during gaming. The GPU? Idels around 60 but with SpeedFan at the above settings, stays around 60 while gaming. This is amazing to me. The case is big and heavy, but quiet and cool.
Conclusion
This shows that an OEM pc, mainly Gateway, can be used for playing the latest games just by upgrading it a little. The x300 could play battlefield 2 even, but the 6600GT simply blows it away. I simply love this pc and wouldn't want anything else if I could do it over again. Thanks for reading this, and I hope I've changed people's idea of how OEM pcs can't be turned into gaming power houses. Sure, I could have bought a 7800GTX, but I'm happy with what I have and It plays BF2 at 1280x1024 which is my LCD's resolution with medium settings on and gets around 60FPS.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic