Check out crucial.com. If they recommend RAM for a specific PC model, they guarantee it works or they take it back.

Many people around these forums buy from crucial for exactly that reason.

please check your user manual or contact Dell to see If they’re supporting with single sided(high density IC)memory module."

That could very well be a problem.

Have a 435T/9000.  Be aware that max RAM is 48GB.  See here for details, pages 5 and 6 (note link discusses both 435T / 9000 and 435MT, but both seem to max at 48GB).  You might want to do 3x8GB to leave option open to go to 48GB later.  435T / 9000 is limited to 1066 speeds, unfortunately. 

Crucial Ballistix Sport will probably give you the lowest CL timings with Kingston HyperX next.  Note 2x8GB packages seem to work (installed in threes, of course), so you could probably mix and match a 2x8GB and single 8GB package of the same memory. 

The Sport's were the fastest timings I could find for the 435T - see here for CL6-6-6-18 timings @ 1066 running in a 435T. Right now there's a good price with a large retailer here - $67 for 2x8GB and $35 for 8GB.  Note 435T ignores XMP and only uses JEDEC settings - you want low JEDEC settings because that's what the machine will use.

Not sure you're aware, but different versions of Windows limit maximum memory.  See Memory Limits for Windows... on Microsoft's MSDN site for imposed limits.  You're good to go if Pro/Ultimate or any version of Windows 10.

TECHGEE: Thanks for the heads up. Rechecked and , I'm OK on this - Vista Home Premium 64.

Back from the ether...

ROHE: Thanks, I had but probably moved on since they did not specify triple channel. Doing so again...
www.crucial.com/.../studio-xps-435

Since I need triple channel, I guess the x4 kits are not viable, but that 3 of one of the 4gb single sticks would be?
The first three of these listed:
9-9-9-24 www.crucial.com/.../CT3579527
8-8-8-24 www.crucial.com/.../CT2452587
8-8-8-24 www.crucial.com/.../CT2457903

Apart from the timing diffs, I do not know how they differ. I think all are:

    DDR3 PC3-12800 • Unbuffered • NON-ECC • DDR3-1600 • 1.5V • 512Meg x 64 •
    upgrade for Dell Studio XPS 435 system.

Lost in moderation...

Thanks, I had but probably moved on since they did not specify triple channel. Doing so again...
www.crucial.com/.../studio-xps-435

Since I need triple channel, I guess the x4 kits are not viable, but that 3 of one of the 4gb single sticks would be?
The first three of these listed:
9-9-9-24 www.crucial.com/.../CT3579527
8-8-8-24 www.crucial.com/.../CT2452587
8-8-8-24 www.crucial.com/.../CT2457903

Apart from the timing diffs, I do not know how they differ. I think all are:

    DDR3 PC3-12800 • Unbuffered • NON-ECC • DDR3-1600 • 1.5V • 512Meg x 64 •
    upgrade for Dell Studio XPS 435 system.

Lost in moderation...

TECHGEE: My recollection is that the max is 24GB. Verified from notes, though page missing:
Studio XPSTM  435 Desktop

http://www.dell.com/content/products/productdetails.aspx/desktop-studio-xps-435?c=us&cs=19&l=en&s=dhs

Up to 24GB Tri-Channel 1066MHz DDR3 SDRAM - 6 DIMMs1

Thanks for the recs. Adjusting for the 24GB max, the 4x3 12GB kit at the link you provided looks pretty good....? (though more $ for less memory)

My recollection is that the max is 24GB. Verified from notes, though page linked missing: 

Thanks for the recs. Adjusting for the 24GB max, the 4x3 12GB kit at the link you provided looks pretty good.... (though more $ for less memory)?

The Crucial fitness guarantee applies only to direct purchases even though they are listed as the seller at the linked site.... Trying to reconcile the product numbers as well.

Check out crucial.com. If they recommend RAM for a specific PC model, they guarantee it works or they take it back. Many people around these forums buy from crucial for exactly that reason.

I've posted two replies to yours ROHE, as below, but they were both lost in moderation.

Thanks, I had but probably moved on since they did not specify triple channel. Doing so again...
www.crucial.com/.../studio-xps-435

Since I need triple channel, I guess the x4 kits are not viable, but that 3 of one of the 4gb single sticks would be?
The first three of these listed:
9-9-9-24 www.crucial.com/.../CT3579527
8-8-8-24 www.crucial.com/.../CT2452587
8-8-8-24 www.crucial.com/.../CT2457903

Apart from the timing diffs, I do not know how they differ. I think all are:

    DDR3 PC3-12800 • Unbuffered • NON-ECC • DDR3-1600 • 1.5V • 512Meg x 64 •
    upgrade for Dell Studio XPS 435 system.

Neither can I tell the diff between these, though I think I'm pretty good to go.

www.crucial.com/SearchDisplay;categoryId=&x=15&y=15&storeId=10151&catalogId=10151&langId=-1&pageSize=10&beginIndex=0&sType=SimpleSearch&searchFor=Keyword&resultCatEntryType=2&showResultsPage=true&searchSource=Q&pageView=

www.crucial.com/.../CT2709316 ??

apparently losing random posts in the ether (moderation), which is where this one will go at least for a good while, as well.

Don't know that you're on moderation.

The forum has been "sick" lately and posts either don't appear at all, or you have to refresh the page ~3-4 times before they finally appear. We're all having these issues. :emotion-41:

Glad you found the right RAM for your upgrade.

Thanks, Ron. My two replies to you, in particular, are still vapored. I didn't mean 'real' moderation, as, under the circumstances that would be absurd, but yes, under 'sick' moderation for which I don't doubt all are liable.

Cheers.

Those 3x4GB Sport's should do nicely and have good timings once in the 435T!

Since Vista Home Premium 64 limits usable memory to 16GB I think you made a good choice.

Note while Dell and Intel spec'd the 435T and X58 Chipset as max 24GB at the time, it has shown to support 48GB once 8GB memory was available.  Oh, and I did stress test the memory for several hours with a memory test tool to make sure it successfully read/wrote the entire 48GB.

Enjoy!

Many thanks for the followup and more good info, TECHGEE.

Much appreciated.