Cpu upgrade for a dell optiplex gx620?

[jackson100]

I have an old dell optiplex gx620 desktop form factor , what's the best supported cpu I can put into it? Will a 64-bit cpu work? I think the motherboard is a 32-bit because it only supports 4gb of ram. I've read that the Pentium D 840 should work, but it's a 64-bit cpu and I want to make sure it will.

 

[Samat]

Pentium D will work with it according to Dell data sheet (pdf), that 4GB limitation comes from the 945G chipset and doesn't affect the cpu support.

 

[bishb25]

I have a Gx620 (Mid Tower) that I've pretty much maxed out.

Pentium D 960 (3.6Ghz Dual Core)
DELL Performance Heatsink J9761 (An absolute must!)
4 GB Ram (only 3.25 GB usable thanks to another Dell #^&'d up mobo design)
EVGA GEFORCE GT640 4GB Video card running dual LCD's
2 SATA Hard Drives (120GB & 250GB respectively)
Stock power supply and fans
Dual Boot: Win 7 Pro 64bit & Kubuntu linux 64bit.

I have read a lot of slagging off of these computers, but I use this rig for my daily computing needs as well as playing my favorite games at moderate graphics settings and favorable frame rates.
Flight Gear Flight Simulator
Euro Truck Simulator 2
Train Simulator 2016
BobCadCam V28 (not a game, but very tough on PC's)

If you're on a budget and don't need the newest, hottest titles at max graphics then you can live with this setup for a long time. I've had it for about 6 or 7 years (and I bought it used on ebay). Though I'd plan on ditching it when Win 7 support ends.

P.S. All of the above being said... If you have a couple of hundred bucks to spend, even a current, low-end, gaming PC will out perform the GX620 by miles.

Good luck!