Which memory for Toshiba A105-S1014?

I tried two different kits of dual-channel, 2x1gb, at DDR2-5300 I think. Neither kit (one from Kingston and one from PNY) would work. On both kits I tried swapping sticks, running only one stick at a time, everything I could think of and nother worked. One I try to turn it on it doesn't even POST, it just restarts about a dozen times and then just turns off. Nothing on the screen. I then tried startign it with NO memory installed and it did the same thing, so with both kits it was as if the mobo wasn't even seeing the RAM.

The comptuer uses a 1.5ghz Celeron M. It has a single 512mb stick of DDR2-4200. I know the two kits were faster memory, but I figured they would automatically clock down and everything would work.

So I've narrowed it down to four possibilities:

1. The kits I was using are just too fast and I need to get a kit of actual 4200.

2. The motherboard does not support dual-channel.

3. The motherboard does not support 1gb sticks (although that seems absurd, I think it should accomodate 2 gigs max)

4. The particular sticks in BOTH kits are, for whatever reason, simply incompatible with this mobo, similar to how some desktop motherboards are finicky and certain brands or manufacturers of memory.

So which is it? Is it a combination of things? The laptop is my dad's. I'm thinking maybe I should just play it safe and get two single 1gb sticks in 4200 and see what happens.

Hmm I own a Toshiba Satellite (my kids use it now) I just bought some kingston PC-6400 off the rack at Bestbuy and it worked just fine...

Do you happen to know the model number? And what are the details on the Kingston? 6400, but how much? Dual-channel?

Some laptops will only accept one-sided memory (memory with the chips on one side of the CB) Both one of my older latitudes and a friend's HP had this problem, both systems were a few years old. Maybe this is your problem?

Something having to do with double-density memory or something....

go to crucial.com and use their memory wizard. Use their recommendation and buy the ram somewhere else.

Thanks, Situman. According to Crucial's site, the Toshiba does support dual-channel, it does support two gigs, and the DDR2 is backward-s compatible as far as speed is concerned. This makes me wonder why the two other kits I helped my dad purchase (and subsequently return) didn't work, considering they were DDR2, in the correct capacity, and were dual channel. Why wouldn't the PNY or Kingston kits work but the Crucial will? Does it come down to the actualy memory manufacturers and mobo compatibility? The single 512mb stick that came with the laptop lists itself as a Hynix unit. Perhaps the PNY and Kingston units are from a different manufacturer and they aren't compatible with the Toshiba? Any further thoughts?

No clue, but buy the exact crucial model# from another site. I only use Crucial or Corsair.