I got a gigabyte ga7n400 pro2 motherboard with an AMD 2800+ barton proc. My temps with mbm5 are reading 45 C under full load with F@H. I have a watercooler setup with a danner mag 3 pump --> dangerden maze 3 waterblock --> procombo radiator from dtekcustoms.com --> reservoir.

45 C seems kind of high with a watercooling setup . . .
It goes down to around 39-41 when idle and if I open the window up to let the cold air come in, the lowest temp I've seen is around 33 C. What's normal for a 2800+?

hmmm... that is a little high, unless you have a very warm room.

my temps on my 2800 are 33 idel and 35-37 deg C load right now. My room temp is 70.5 deg F, I get this from my 2 temp probes hanging 6" off the cieling of my computer room. But I am using a S-RBX with a L30 pump and thermochill 120.2. You may need to reset your block, and what thermal interface material are you using (Artic Silver 3, 5, cremique)?

Also what is your cpu running at? what is your vcore? are your fans running @ 12volts or 7volts?......

you should be getting about 30-38c but are you using artic silver and where is your rad located, also are you using water wetter, if so make sure your water is not too pink clear with a light pink tint is good. Hit me up with some more info, like room temp and are you overclocked and well etc.
If you are using artic silver don't use to much and maybe try remounting the block.

Are you running "PR3ACH3RS HARDM3NU F-13" bios?
You mentioned if you lowered your ambient your temps dropped, thats a good sign everything is working. Download and flash to the latest pr3ach3rs offering...It sorts all the bull in the stock bios out...We got the same board and it rocks,it even makes easy tune 4 operable and readings for temps there are closer to the real thing.

i'm thinking its because i had to use a socket hold down block. It doesn't seem like it's applying as much pressure as the motherboards with the holes for the waterblock mountings. I'm going to try to remount it and add another spacer so the springs apply more pressure.

I used water wetter and the water is a light pink. Its translucent. In my bay reservoir though (i have one that has the center channel to cut down turbulence), the side that the input is coming through the water is pink and clear but the side that the water goes to the pump on, is kind of murky and i see some white crud forming on the bottom. anyone know how i can get rid of them?

Radiator is located at the top of my case.

Wow those temp are kinda high. I have my barton 2800 oc to a 3000 and my temps are 36° idle and 40° load with air (Zalman CNPS3100-Plus, off brand 92mm fan) and its 79°F in here.