Dell Dimension 4700 RAM upgrade to 4GB doesn't work, causes bizarre behavior

Sometimes upgrading memory seems to be an arcane art.  The Dimension 4700 has a dual channel memory controller; the different colors on the memory socket latches are indicators of which slots are supposed to have matched memory modules.  You should keep the original memory together and the new memory together.  There may still be a problem, however, if the characteristics of the new and old memory are very different.  The controller is supposed to fall back to the speed of the slowest memory because all the memory must be run at the same speed.

You seem to have gone through most of what I would do already; tried the new memory in the first pair of slots and the old in the last pair.  Did you try it the other way round, leaving the original memory in the original slots and placing the new memory in the last pair?  After that, the only thing I can think to do is to reset the CMOS by removing the CMOS back-up cell for five or ten minutes.  Unplug the power, push the power button and hold it in for ten to twenty seconds to discharge the power supply keep-alive voltage, remove the CMOS battery, push the power button and hold it in for another ten to twenty seconds to discharge the back-up battery circuits, replace the battery after the ten minute period has expired, connect everything and try again.  Sometimes forcing the computer to re-detect all its devices helps with this sort of problem.

If that doesn't help, the specs on the old and new modules may just be too different to allow the memory controller to find common operating parameters.

Jack, let me clarify. I've got two identical sets of the new memory. I don't have to use the old memory at all. I've got four cards of 1 Gig each. So, two of them (any two) work in the white set and when I put additional two in the black set it goes haywire.

I did misunderstand that part, but my suggestion to reset the NVRAM is still a good idea.  Sometimes these problems are caused by a mismatch between the stored configuration of the machine and what is actually in it.  If resetting the NVRAM doesn't do it, then I am as puzzled as you.

EDIT:  One other question I neglected to ask; when you install the RAM you can go to System Setup and see what the controller thinks of your memory.  If the memory is sufficiently matched in timing your BIOS will report that the memory is in dual channel mode.  Otherwise you will get single channel operation.  Memory vendors will frequently make a match for you so that you can purchase a set of modules that are guaranteed to match closely enough that your computer will run in dual channel.  I don't think this has a direct bearing on your complaint but operation in single channel mode will slow things down a bit.

2 sets is not the same as 4 pieces of identical vendor memory.  Some Vendors do not play nice together.

Are they ALL the same vendor and All the same speed and ALL the same wait states?  

32 Bit os is limited to 3.25 to 3.5 gigs of useable ram.

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Uh, I feel really really stupid, but, after I went and tested all the slots separately, including the black ones, and then put everything in again, the four cards together worked. Apparently, I'm guessing, I didn't put them in securely enough before, although, in my defense, I really did check for this several times. Thanks for your help, guys. Oops (sheepish grin).

Now I have a different problem though. It's only reading 3 gigs of memory. A quick Internet search shows that this is a 32 bit operating system limitation and that I have to upgrade to a 64 bit system to effectively use all four cards. :-/.

I've read this whole feed and it seems to be helpful.  Although, I would like to venture out (mostly to save money) and fix my computer myself.  I'm very good with software, but I've never messed with the inside of a cpu before except just to see what was inside.  My computer is a 4700 as well, but I have Windows 7.  The guy that fixed it recently for me replaced Windows XP (which is what I had) with windows 7.  Should I take some lessons from Youtube and try to figure out what the motherboard and all that junk is all about so I can install more RAM *much need* on my cpu, or should I pay money to get it installed for me?  (I don't want to break my computer.)

thanks.

The 4700 chipset with PCI-E 1.0 and DDR2 ram is too old. Any money invested is a waste.

Newer systems like the Optiplex 620 and up are VERY inexpensive.

And come with windows 7 or 8 or 10 for the cost of windows alone.

A better choice for tradeup to used PC is the Precision 380 or T3400.

http://www.ebay.com/sch/i.html?_nkw=dell+precision+380

http://www.ebay.com/sch/i.html?_nkw=dell+precision+3400

http://www.ebay.com/sch/i.html?_nkw=dell+precision+3500

The best choice is the Precision T3500 if you can find it for a reasonable price.

Systems as old as the GX620 can be updated to run 64 bit windows 8.1 or even 10 with little effort.  Investments in them can be carried forward to newer and newer machines aka Directx 11 PCI-E video cards can be used well into the next Decade.

http://www.walmart.com/search/?query=Optiplex%20Tower&sort=price_low&cat_id=3944_3951_132982_1224739&facet=brand:Dell

SpeedStep you are incorrect.

The Dell Dimension 4700 is not AGP and DDR 1.

It is PCI Express (It has a dual-width x16 graphics slot, an x1 slot (and 2 conventional PCI slots)) and Dual-Channel DDR2.

I know this as I've had two 4700's and upgraded them both (got the first one in 2004) and I'm using the newer 4700 right now.

247- So why are you responding to a thread that's from 2011?

DDR1 and DDR2 are no longer available in the retail channel.  2 Gig Low Density INTEL compatible ram is going to be hard to find.  The newer systems suggested support Pentium D processors which allow installation of windows 8 or 10.  In most cases its not worth while upgrading a netburst Pentium 4 system.

The PCI-E 1.0 bus in these older chipsets is not likely to work with newer cards and will not work at all with UEFI based cards like the Radeon R series.

The Dimension 4700 has four RAM slots and supports up to 4 GB when four 1 GB DIMMs are installed (two 2 GB DIMMs were installed in my first 4700 at one stage and it seemed to work fine but I'm guessing it probably shouldn't be done that way) however Windows will only see around 3 GB or so even on 64-bit. I don't think the 4700 requires Low Density RAM but I'm just guessing.

I have a Pentium 4 in my 4700 and I was using Windows 7 + XP before and now I'm just using Windows 10. Some years ago I installed a Pentium 4 661, 3.6 GHz (0F65h SL9KD D0) (cost a few dollars on eBay) which is 64-bit and supports CMPXCHG16b, PrefetchW, and LAHF/SAHF so even 64-bit Windows 10 can be installed on the 4700.

It might not work with all new graphics cards but I just bought an EVGA NVIDIA GeForce GTX 1050 Ti SSC (4 GB) to replace my old GT 240 (512 MB) and it works fine.

The newer 4700 motherboards are possibly PCIe 1.1 not PCIe 1.0a

Screenshot from GPU-Z on my Dimension 4700: