Adding 2 RAM sticks makes my CPU overheat

[kotch]

I'm trying to install a second pair of identical RAM in my system to get 4 total. All runs fine and well with 2 sticks and my CPU idles at 35 C. When I attempt to add the second pair of RAM sticks, it boots up, but then shuts down a few minutes later. This is because the CPU temp has risen to 90 C, and I even saw it at 120 C one time. What's going on? I've tried relaxing the timings and upping the voltage, but I can't figure out why the CPU overheats with the addition of RAM.

-ASUS P5N32-E SLI LGA 775 NVIDIA nForce 680i SLI ATX Intel Motherboard
-EVGA 640-P2-N825-AR GeForce 8800GTS 640MB 320-bit GDDR3 PCI Express x16 HDCP Ready SLI Supported Video Card
-Intel Core 2 Duo E6750 Conroe 2.66GHz LGA 775 65W Dual-Core Processor Model BX80557E6750
-COOLMAX CW-650T 650W ATX12V / EPS12V SLI Certified CrossFire Ready Active PFC Aluminum Power Supply
-Western Digital Caviar SE16 WD2500KS 250GB 7200 RPM SATA 3.0Gb/s 3.5" Hard Drive -
-G.SKILL 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model F2-6400CL5D-2GBNQ

[Gizmo]

What happens if you REPLACE your existing RAM with the new RAM?

[cloasters]

Could air flow in your case be disturbed by this new RAM arrangement? If so, perhaps more powerful case fans are indicated.

[chrisbard]

Never heard of this problem before. First thing that came to mind was that you stick the mem into the CPU fan but then I said to myself neah he wouldn't do that If you test the RAM and they all work just fine just not all 4 at once I suspect the mobo.

[kotch]

all RAM sticks work individually and in pairs. It's just when all 4 are installed where there is a problem. The extra two sticks don't block a fan. It might inhibit airflow a bit, but a 60 C jump??? I'm stumped.

[Daniel ~]

Swap you old ram for your new ram and use the old ram slots...if that doesn't heat you up try your Old ram without your new ram in the slots that you weren't using and see it you maintain the same temps.

This is a new one to me as well!

[kotch]

As I said, any configuration with just 2 RAM sticks (old, new, mixed, either pair of RAM slots) works fine. It's just when all 4 are in that the CPU reacts by reaching the critical shutdown temperature.

[Gizmo]

I've got to be suspicious of either the PSU or the mobo. Seeing as it's a Conroe, the CPU doesn't really care what the memory configuration is. If it was a CPU with integrated memory controller (Core i7 or Athlon64 family), then I'd suspect the CPU, but as it is, there's absolutely no reason the RAM should have any impact on the CPU temps.

TBH, the PSU is a long-shot, but is a possibility. The mobo seems the more likely culprit.

[MUff1N]

My first thought (hunch) is there's a short in one of the other memory slots.
Now if you tried putting the RAM in the 2 other slots that are normally empty & it still runs cool then I'm stumped other than it being something wrong with the mobo or memory controler like Gizmo said.

But I have NEVER heard of this problem before...

[cloasters]

It's usually not pointed out in the mainboard's manual, but boards that run happily with all four RAM slots filled are a bit rare. But this still doesn't explain the heat issue. MUff1N's hunch may be right.

[noob]

Sounds like a mobo problem. I would say in your power distribution lines.

Firstly a visual inspection to check your capacitors, if there are some swollen/leaking you have found your problem.

Longshot:
Stick all 4 sticks in, go straight to BIOS and see if there is a change in voltages - it may show something but probably not.

If you can use a DMM to manually check the voltages going to the CPU and RAM. Unfortunately you probably can't check the current, which it may be shorting somewhere and providing a whole lot more juice than the CPU wants. It may have overvoltage protection but probably not overcurrent protection.

If you possibly can, check all of your current gear on a different mobo, either that or change out your PSU.

[robbie]

Maybe just try to flash it to the latest bios version. (might be a bug)

[danrok]

Originally Posted by robbie

Maybe just try to flash it to the latest bios version. (might be a bug)

I agree, first step would be to verify that it really is that hot, and not just a misreading/bug.

[cloasters]

Any daylight with this unusual problem, kotch?