Maybe the tester got a messed up packaging or something, but the one I got most certainly didn't rattle around loose in the box and I have never heard of this brand or model having a high RMA rate.
Just sayin.
RAM - This is what I meant
metal orient :
Crucial 8GB (2x4GB) DDR3 Ballistix Sport Memory Kit CL10 1.5V £29.99
http://www.ebuyer.com/275166-crucial-ballistix-sport-8gb-2x4gb-ddr3-1600mhz-memory-kit-cl10-1-5v-bl2kit51264ba160a
which IS Crucial RAM which is why it says Crucial on it.
The AP3 most definitely isn't on the tool which is why I would avoid it, not to mention it costs more money when the OP is trying to shave from the budget.
Returning to the PSU issue, JohnnyGuru may have given both of them the same rating, I won't argue about that. I will say, though, that ratings are subject to a lot of things. A 650w rated XFX isn't the same thing as a 650w Diablotek after all or we wouldn't even be having this discussion.
That being said, I do sit around many hours each day and help people troubleshoot technical problems and whereas I have never diagnosed a problem caused by an XFX PSU I have diagnosed many problems related to OCZ PSUs including those where a BANG was involved.
I have also read reports on fail rates for major brand things and I can tell you that OCZ is leading the way in RAM and SSD failures as well.
OCZ doesn't really compete for the highest quality spot in most any category. In PSUs they usually give modular to make up for the lower quality at the same price, for instance.
Other prices, they compete on things like price to lure away buyers from other brands.
Not that they are horrible, but I wouldn't trust my computer to OCZ and I wouldn't advise anyone else to do it either unless cheap modular is a fixed requirement.
OCZ has historically outsourced its PSUs to FSP, 3y, and Topower. FSP being their OEM of choice most of the time its likely the ZS is a FSP OEM PSU.
Regardless of what it is, none of those OEMs hold a candle to Seasonic as an OEM. They don't even try.
Note, FSP is also used by many generic brand manufacturers who design "700w" units that put out 300w in reality. This is never the case with Seasonic OEM PSUs.
OCZ did buy its way into better PSU designers when it acquired PC P&C, but its still not in the same ballpark as Seasonic is.
Again, I am not going to go as far as saying OCZ is actively bad like Diablotek is or anything, but I am not going to use it or advise others to use it. Nor am I going to smoke or advise others to do so.
The OP is trying to shave and going with an OCZ PSU may not be the worst way to go about it, but I would use it as a last resort.
I would rather suggest an XFX 550w instead which lists itself as 52 GBP inc vat like here
https://www.aria.co.uk/Products/Components/Power+Supplies/650W+or+less/550W+XFX+Core+Edition+80PLUS+Bronze+Power+Supply+%5BP1-550S-UKB9%5D+?productId=45332
or even go as far as an XFX 450w for 42 GBP inc vat
https://www.aria.co.uk/Products/Components/Power+Supplies/650W+or+less/450W+XFX+Core+Edition+80PLUS+Bronze+Power+Supply+%5BP1-450S-U2B9%5D+?productId=45329
These could be available elsewhere for cheaper too. I didn't search around for the cheapest place to get these things or anything like that. Both of them should probably work just fine although with increased average load the longevity may be lower.
Dropping back to 6770 or 6790 is still on the table too if performance is to be sacrificed in order to shave significantly off the budget. Both are still very far ahead of the current 5450. It would pain me to see this route taken, but it would free up a sizeable chunk.
The OP did manage to get the Windows 7 through school too it seems like so that freed up 50 GBP as well.
Case/Cooling setup - I am having a difficult time finding good information on the specifications of the case and the motherboard for the iMedia X2424. Maybe because it is kinda old now. However, it does look like a micro only case, so I am not sure if it will fit the motherboard we have chosen.
At this point I think I will have to suggest dropping back to this motherboard instead of the one chosen originally P8H61-M LE just to make sure it it can fit inside the case. Here
http://tinyurl.com/7awxvso
it says it is 46 GBP inc vat which is a decent savings and still should do the job OK.
This RAM works with it for 29 GBP
http://www.ebuyer.com/172949-kingston-8gb-2x4gb-ddr3-1333mhz-i5-memory-kit-non-ecc-cl9-1-5v-kvr1333d3n9k2-8g
per its QVL. I don't trust Kingston as much as I do Crucial, but I do know that Kingston RAM tends to be very low in failure rates.
I would rather stick with the original setup, but I can't trust that it will fit the case and I don't want to suggest buying a new case either, so I will go out on a limb and recommend the Asus motherboard / Kingston RAM combo. Possibly with the XFX 550w or 450w if necessary to shave more off the budget, if necessary.