(2x1gb) running with (2x512)?

[underbyte18]

So I am Wintec AmpX (2x512) Running in my system. They are DDR2 800.
I want to upgrade with (2x1gb). My friend mentioned that it could cause some problems in my build? I am not sure why. Basically it would be four DDR@2 800's, only half are 512 and the other 1gb. Is there a problem?

 

[gent]

System spec (specially MoBo and RAM sticks)?

 

[underbyte18]

GIGABYTE GA-M55SLI-S4 Socket AM2 NVIDIA nForce4 SLI ATX AMD Motherboard
RAIDMAX RX-9 SE ATX-911SEB Black SECC Steel ATX Mid Tower Computer Case
HIS Hightech H165PRQ512N-R Radeon X1650PRO 512MB GDDR2 PCI Express x16 IceQ Video Card
LOGISYS Computer PS550ABK ATX12V 550Watts Power Supply With SATA and 20/24 Pin connectors.
AMD Athlon 64 X2 5000+ Windsor 2.6GHz Socket AM2 Processor Model ADA5000CSBOX
WINTEC AMPX 1GB (2 x 512MB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model 3AXT6400C5-1024K
Western Digital Caviar SE WD1600JS 160GB 7200 RPM SATA 3.0Gb/s Hard Drive -
Arctic Silver 5 Thermal Compound

 

[gent]

*should* work OK, however be aware that Wintec RAM isn't listed (by Gigabyte) as being compatible, it's one of the cheapest makes and problems have been reported on various forums (including this one).