4 x 1GB on P5B = black screen


Apr 17, 2008
* OCZ part number:-OCZ2P800R22K
* Module size and kit size:-4 x 1GB
* CPU model and rated speed:-Intel E6750 Boxed
* Overclocked CPU speed:-defautl
* Divider and FSB used:-
* Motherboard and revision:-Asus P5B
* Motherboard Bios rev:-newest (1803)
* Video card:-Nvidia 8800GT 512MB
* Power supply:-Xilence 550 Watt
* Operating System:-XP SP2
* CPU and System Cooling:-Boxed and normal temps
* CPU and System temps:-normal
* Purchased at/on:-Atelco Germany, Feb 08
* Country:-Germany
* Memory voltage:-1.8

I bought a new PC in December with Asus P5B Motherboard and and a 2GB Kit from OCZ:

2048MB-KIT OCZ DDR2 PC2-6400 Platinum Revision 2 Dual Chanel CL4

It runs perfectly and so i decided to upgrade my RAM to 4GB.

Yesterday I got the same RAM again and now I'm a proud owner of 4 x 1GB RAM!

But when i put the 2 new sticks in the slots and then turned on my PC only the Cooling starts but I don't see anything on my screen, my PC does not even make a sound like BEEP...

I tested every single RAM alone and they all work on every single bank...

So I googled and found a thread where someone posted that you have to raise the RAM Voltage to 2.1. Is that correct?

My second problem is that my ASUS P5B downgrades my 800 RAM to CL5 even the RAM is able to run at CL4... ASUS said that it's a chipset problem...

Is there any solution for it?

Thanks in advance!



With 4 sticks in, there could be a voltage drop (vdroop) that is causing the problem; so yes, boot with one stick, and bump up the voltage a little to compensate.
Not sure on the CL5 question but I think I have read about that problem when 4 sticks are used on some boards. If ASUS says it is a chipset problem, then you may be out of luck on a fix.


Nov 2, 2006
You likely need to increase your NB (aka memory controller) voltage to compensate for the load of 4 modules. You need to set your memory voltage to the setting recommend by the manufacturer.


Mar 2, 2007
I have the same MB. I built my rig about 1 1/2 ago. I started with 1GB (2x512) ddr2 800 ram Corsair. I then upgraded to another (2x512) Corsair for a total of 2GBs of ram. As soon as I added the ram, I had the exact same problem. The fan would start, but then nothing. I played with the RAM fitting, I swithced all the RAM around. I did this for 2 days, continually swithing, playing with the fit, putting only 1 stick , 2, 3, all 4, tried all 4 slots, absolutely nothing happened, still no boot up. On the 3rd day, I tried one more time, and by some miracle of God, it booted up. I have no idea why, I did nothing different from the previous 2 days. Since then I have not touched the RAM..
So you can try the RAM voltage suggestions, if that doesnt work, you can just play with it like I did and hope for the best. In hindsight, this MB is rather weak. Not great for OC and after my RAM debacle, I really wish I would have gone with a higher end model.


Jul 6, 2004
I have a P5B Deluxe board and just upgraded from 2 1gb sticks to 4 1gb sticks for a total of 4gb ram (Corsair xms2 6400c4). Upon startup bios only detected 2gb ram. I then enabled memory remapping in bios and now it detects all 4gb's. System boots into windows fine. However XP SP2 only detects 2gb in properties. It should detect at least 3GB. Still working on that problem.