[GlennCMC70]

Had a video card die on me overnight couple nights ago (fan fell off and cooked the chip). I got a new video card (Radeon HD 5450 2G DDR3) and while I was there I thought I would up the RAM.
Video card works great so far.

Now for the problem involving the RAM. PC is a eMachines T5212. Originally came w/ 512M RAM x2. Mitch was nice enough to give me a pair of G.Skill 2G cards (they say DDRII2GB PC2-6400). I installed them and discovered one of the 2 was bad (he told me this could be the case when he gave them to me). I was OK w/ it since I was moving from 2 512M cards (1G) to 1 2G card. I was 2 times better off w/ just the one card. So forward to today where I pick up a pair of PNY 2GB cards to populate both slots (to get 4GB total). They are DDR2 PC2-6400's. Neither will work in my PC. I tried both one at a time in slot 0 and the PC would not boot.
So I find a site that says it can scan my PC and tell me what RAM would work. This is what I get:

DDR2 PC2-5300
Memory Type: DDR2 PC2-5300, DDR2 (non-ECC)
Maximum Memory: 2GB
Currently Installed Memory: 2GB
Total Memory Slots: 2
Available Memory Slots: 1

2GB

DDR PC2-6400 EMPTY

Each memory slot can hold DDR2 PC2-5300 with a maximum of 1GB per slot.*

It is the last line that has me confused. It says my PC will only take a 1GB card per slot for a max of 2GB total. But I have a 2GB card in slot 0.
Is this just an issue of the G.SKILL card working where it shouldn't? I checked the bios and it see's the G.Skill card as 2048MB in slot 0. Should I seek out a G.Skill card (2 of them)?

[JimMueller]

I have an old eMachine T3256 and I couldn't find any memory that was completely compatible due to their restricted BIOS and crippled mainboard. I thought perhaps it was due to some special CAS/RAS timing they used but I gave up on it. When I called eMachines they offered to sell me more of their supported RAM though; I didn't buy it and just decided to never buy their product again. I installed a hacked BIOS to open up the BIOS and it didn't overclock very well.

This site indicates you should be using PC2-4200 RAM:
http://www.memorystock.com/eMachineseMachinesT5212.html
This site indicates you should be using PC2-5300 RAM:
http://www.crucial.com/store/listparts.aspx?model=T5212

I tend to believe Crucial over MemoryStock. I've read other threads about your model only recognizing the RAM in bank 0 and not in bank 1. Both modules worked individually but weren't recognized together. Going out on a limb, perhaps put the pair of 512MB modules back in and see if your diagnostic tool will tell you the RAM timings on the chips. They may also be listed on the modules themselves, something like 7-7-7-21, 9-9-9-24, etc. Then remove the 512MB modules and put in each 1GB module one at a time in bank 0 and see if the RAM diagnostic reports the same timings? Hope you have better luck than I did.