Odd problem with Memtest, Prime95 and Kingston HyperX PC5400

You can see my system specs in my signature if you want to know what it's got under the hood.

The issue is with a 1gb Kingston HyperX PC5400 DDR2 Memory Kit. I built this system and it's ran pretty well. I've had it at 3.75 and the Memory running at DDR711. I decided to run both Memtest 86+ and OCZ Memtest 86 to see if I was getting any errors. I found that one of my memory modules was generating errors in Test 1. I even slowed things down into the 533mhz range and still got an error or two running 4-4-4-12 timings.

So I figured I've got a bad stick, so I order up an RMA replacement from Kingston and pay for an advanced exchange. Those new memory modules showed up today. So I crank the CPU up to 3.85, DDR733 and do a quick Memtest. I see errors using the original modules.

I pull them out and install the fresh modules from Kingston. I re-run Memtest only to come up with the tests clean. I let it run for about 8 passes, no problems even at only 1.9v.

I'm thinking problem solved. So I try to boot Windows XP and it gets just about to my desktop and blue screens. I've never had this system bluescreen so immediately I know it's the memory. I go into the bios and set the memory up to 2.0v and 1.65v on the chipset and reboot. Same deal, if I'm lucky I'll get to the desktop but anything much blue screens the system.

So for grins I start swapping out 1 stick at a time with my original sticks. One of my oriiginal sticks generates errors, while the other one does not. Okay cool, I figure I'll use the 1 known good stick from the first batch and pair it up with 1 of the 2 new sticks to make a new pair. System is a little better, but still blue screens.

Drop the two original modules in, bam I'm running dual Prime95 without error, no blue screen.

I have a couple possible ideas. The first being that my original modules were not tossed into the system running a 700mhz DDR clock right off the bat. So perhaps over the initial few days, they broke in a bit. Maybe I need to do some stress testing with these new modules at lower speeds and them bump them up to see if I run into the same problem. Has this happened to anyone else with Kingston memory in the past?

The other is that the two modules I just got are not happy at that speed, even though they are error free in Memtest. In this case do I just keep my originals and pretend I never fired up Memtest?

What do you guys think? It sure seems a bit strange to me. Also the memory modules all share the same revision number, so I don't think anything significant has changed with the module design. After all, this stuff has not been out very long.

Thanks!

While you have all sticks, I would do a burn-in with SiSoft's sandra, see if that helps out your new sticks

Already one step ahead of you. I decreased my memory clock to about 678mhz and am running dual prime95 and the sandra memory burn in while I'm at work with the new sticks.

The system crashed last night while running Prime95 with the old sticks, so I'm kind of screwed either way at this point.

how does the memory stick do when you run cpu and memory at default speed

One of the original stick will throw up and error or two in Memtest at the stock speeds. The new sticks have yet to error in Memtest even at DDR733.

was that after the burn-in? Cuz I never heard that it did a great deal of help, but it seemed to help you